diff --git a/pkg/corerp/renderers/container/manifest.go b/pkg/corerp/renderers/container/manifest.go
index 538832bdc4..6061cce165 100644
--- a/pkg/corerp/renderers/container/manifest.go
+++ b/pkg/corerp/renderers/container/manifest.go
@@ -161,15 +161,6 @@ func getServiceAccountBase(manifest kubeutil.ObjectManifest, appName string, r *
 	return defaultAccount
 }
 
-func getObjectMeta(metaObj metav1.ObjectMeta, appName, resourceName, resourceType string, options renderers.RenderOptions) metav1.ObjectMeta {
-	return metav1.ObjectMeta{
-		Name:        kubernetes.NormalizeResourceName(resourceName),
-		Namespace:   options.Environment.Namespace,
-		Labels:      labels.Merge(metaObj.Labels, renderers.GetLabels(options, appName, resourceName, resourceType)),
-		Annotations: labels.Merge(metaObj.Annotations, renderers.GetAnnotations(options)),
-	}
-}
-
 // populateAllBaseResources populates all remaining resources from manifest into outputResources.
 // These resources must be deployed before Deployment resource by adding them as a dependency.
 func populateAllBaseResources(ctx context.Context, base kubeutil.ObjectManifest, outputResources []rpv1.OutputResource, options renderers.RenderOptions) []rpv1.OutputResource {
@@ -238,3 +229,34 @@ func patchPodSpec(sourceSpec *corev1.PodSpec, patchSpec []byte) (*corev1.PodSpec
 
 	return patched, nil
 }
+
+func mergeLabelSelector(base *metav1.LabelSelector, cur *metav1.LabelSelector) *metav1.LabelSelector {
+	if base == nil {
+		base = &metav1.LabelSelector{}
+	}
+
+	return &metav1.LabelSelector{
+		MatchLabels:      labels.Merge(base.MatchLabels, cur.MatchLabels),
+		MatchExpressions: append(base.MatchExpressions, cur.MatchExpressions...),
+	}
+}
+
+func mergeObjectMeta(base metav1.ObjectMeta, cur metav1.ObjectMeta) metav1.ObjectMeta {
+	return metav1.ObjectMeta{
+		Name:        cur.Name,
+		Namespace:   cur.Namespace,
+		Labels:      labels.Merge(base.Labels, cur.Labels),
+		Annotations: labels.Merge(base.Annotations, cur.Annotations),
+	}
+}
+
+func getObjectMeta(base metav1.ObjectMeta, appName, resourceName, resourceType string, options renderers.RenderOptions) metav1.ObjectMeta {
+	cur := metav1.ObjectMeta{
+		Name:        kubernetes.NormalizeResourceName(resourceName),
+		Namespace:   options.Environment.Namespace,
+		Labels:      renderers.GetLabels(options, appName, resourceName, resourceType),
+		Annotations: renderers.GetAnnotations(options),
+	}
+
+	return mergeObjectMeta(base, cur)
+}
diff --git a/pkg/corerp/renderers/container/manifest_test.go b/pkg/corerp/renderers/container/manifest_test.go
index 12684ddf97..f2637754ec 100644
--- a/pkg/corerp/renderers/container/manifest_test.go
+++ b/pkg/corerp/renderers/container/manifest_test.go
@@ -49,6 +49,160 @@ var (
 	testOptions = &renderers.RenderOptions{Environment: renderers.EnvironmentOptions{Namespace: "test-ns"}}
 )
 
+func TestMergeLabelSelector(t *testing.T) {
+	labelMergeTests := []struct {
+		name     string
+		base     *metav1.LabelSelector
+		cur      *metav1.LabelSelector
+		expected *metav1.LabelSelector
+	}{
+		{
+			name: "base is nil",
+			base: nil,
+			cur: &metav1.LabelSelector{
+				MatchLabels: map[string]string{
+					"key1": "value1",
+				},
+				MatchExpressions: []metav1.LabelSelectorRequirement{
+					{
+						Key:      "key2",
+						Operator: metav1.LabelSelectorOpIn,
+						Values:   []string{"value2"},
+					},
+				},
+			},
+			expected: &metav1.LabelSelector{
+				MatchLabels: map[string]string{
+					"key1": "value1",
+				},
+				MatchExpressions: []metav1.LabelSelectorRequirement{
+					{
+						Key:      "key2",
+						Operator: metav1.LabelSelectorOpIn,
+						Values:   []string{"value2"},
+					},
+				},
+			},
+		},
+		{
+			name: "base includes matchLabels",
+			base: &metav1.LabelSelector{
+				MatchLabels: map[string]string{
+					"key1": "value1",
+				},
+			},
+			cur: &metav1.LabelSelector{
+				MatchLabels: map[string]string{
+					"key2": "value2",
+				},
+				MatchExpressions: []metav1.LabelSelectorRequirement{
+					{
+						Key:      "key2",
+						Operator: metav1.LabelSelectorOpIn,
+						Values:   []string{"value2"},
+					},
+				},
+			},
+			expected: &metav1.LabelSelector{
+				MatchLabels: map[string]string{
+					"key1": "value1",
+					"key2": "value2",
+				},
+				MatchExpressions: []metav1.LabelSelectorRequirement{
+					{
+						Key:      "key2",
+						Operator: metav1.LabelSelectorOpIn,
+						Values:   []string{"value2"},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tc := range labelMergeTests {
+		t.Run(tc.name, func(t *testing.T) {
+			actual := mergeLabelSelector(tc.base, tc.cur)
+			require.Equal(t, tc.expected, actual)
+		})
+	}
+}
+
+func TestMergeObjectMeta(t *testing.T) {
+	mergeObjectMetaTests := []struct {
+		name     string
+		base     metav1.ObjectMeta
+		cur      metav1.ObjectMeta
+		expected metav1.ObjectMeta
+	}{
+		{
+			name: "base is empty",
+			base: metav1.ObjectMeta{},
+			cur: metav1.ObjectMeta{
+				Name:      "name",
+				Namespace: "namespace",
+				Labels: map[string]string{
+					"key1": "value1",
+				},
+				Annotations: map[string]string{
+					"key2": "value2",
+				},
+			},
+			expected: metav1.ObjectMeta{
+				Name:      "name",
+				Namespace: "namespace",
+				Labels: map[string]string{
+					"key1": "value1",
+				},
+				Annotations: map[string]string{
+					"key2": "value2",
+				},
+			},
+		},
+		{
+			name: "override name and namespace",
+			base: metav1.ObjectMeta{
+				Name:      "base",
+				Namespace: "base namespace",
+				Labels: map[string]string{
+					"key1": "value1",
+				},
+				Annotations: map[string]string{
+					"key1": "value1",
+				},
+			},
+			cur: metav1.ObjectMeta{
+				Name:      "name",
+				Namespace: "namespace",
+				Labels: map[string]string{
+					"key2": "value2",
+				},
+				Annotations: map[string]string{
+					"key2": "value2",
+				},
+			},
+			expected: metav1.ObjectMeta{
+				Name:      "name",
+				Namespace: "namespace",
+				Labels: map[string]string{
+					"key1": "value1",
+					"key2": "value2",
+				},
+				Annotations: map[string]string{
+					"key1": "value1",
+					"key2": "value2",
+				},
+			},
+		},
+	}
+
+	for _, tc := range mergeObjectMetaTests {
+		t.Run(tc.name, func(t *testing.T) {
+			actual := mergeObjectMeta(tc.base, tc.cur)
+			require.Equal(t, tc.expected, actual)
+		})
+	}
+}
+
 func TestFetchBaseManifest(t *testing.T) {
 	manifestTests := []struct {
 		name     string
diff --git a/pkg/corerp/renderers/container/render.go b/pkg/corerp/renderers/container/render.go
index e93338f3c6..05f93340c5 100644
--- a/pkg/corerp/renderers/container/render.go
+++ b/pkg/corerp/renderers/container/render.go
@@ -612,14 +612,13 @@ func (r Renderer) makeDeployment(
 	outputResources = append(outputResources, *roleBinding)
 	deps = append(deps, rpv1.LocalIDKubernetesRoleBinding)
 
-	deployment.Spec.Template.ObjectMeta = metav1.ObjectMeta{
-		Labels:      podLabels,
-		Annotations: map[string]string{},
-	}
+	deployment.Spec.Template.ObjectMeta = mergeObjectMeta(deployment.Spec.Template.ObjectMeta, metav1.ObjectMeta{
+		Labels: podLabels,
+	})
 
-	deployment.Spec.Selector = &metav1.LabelSelector{
+	deployment.Spec.Selector = mergeLabelSelector(deployment.Spec.Selector, &metav1.LabelSelector{
 		MatchLabels: kubernetes.MakeSelectorLabels(applicationName, resource.Name),
-	}
+	})
 
 	podSpec.Volumes = append(podSpec.Volumes, volumes...)
 
diff --git a/pkg/corerp/renderers/container/render_test.go b/pkg/corerp/renderers/container/render_test.go
index 6bb274415d..0592f0d179 100644
--- a/pkg/corerp/renderers/container/render_test.go
+++ b/pkg/corerp/renderers/container/render_test.go
@@ -17,6 +17,7 @@ limitations under the License.
 package container
 
 import (
+	"encoding/json"
 	"fmt"
 	"testing"
 
@@ -34,6 +35,7 @@ import (
 	resources_azure "github.com/radius-project/radius/pkg/ucp/resources/azure"
 	resources_kubernetes "github.com/radius-project/radius/pkg/ucp/resources/kubernetes"
 	"github.com/radius-project/radius/test/testcontext"
+	"github.com/radius-project/radius/test/testutil"
 
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/require"
@@ -1700,6 +1702,89 @@ func Test_Render_StrategicPatchMerge(t *testing.T) {
 	require.ElementsMatch(t, expectedContainers, deployment.Spec.Template.Spec.Containers)
 }
 
+func Test_Render_BaseManifest(t *testing.T) {
+	manifestTests := []struct {
+		name      string
+		inFile    string
+		container datamodel.ContainerProperties
+		outFile   string
+	}{
+		{
+			name:   "merge container, envvars, and volumes",
+			inFile: "basemanifest-input-merge.yaml",
+			container: datamodel.ContainerProperties{
+				BasicResourceProperties: rpv1.BasicResourceProperties{
+					Application: applicationResourceID,
+				},
+				Container: datamodel.Container{
+					Image: "someimage:latest",
+					Env: map[string]string{
+						envVarName1: envVarValue1,
+						envVarName2: envVarValue2,
+					},
+					Volumes: map[string]datamodel.VolumeProperties{
+						"ephemeralVolume": {
+							Kind: datamodel.Ephemeral,
+							Ephemeral: &datamodel.EphemeralVolume{
+								VolumeBase: datamodel.VolumeBase{
+									MountPath: "/mnt/ephemeral",
+								},
+								ManagedStore: datamodel.ManagedStoreMemory,
+							},
+						},
+					},
+				},
+			},
+			outFile: "basemanifest-output-merge.json",
+		},
+		{
+			name:   "inject new sidecar",
+			inFile: "basemanifest-input-addcontainer.yaml",
+			container: datamodel.ContainerProperties{
+				BasicResourceProperties: rpv1.BasicResourceProperties{
+					Application: applicationResourceID,
+				},
+				Container: datamodel.Container{
+					Image: "someimage:latest",
+					Env: map[string]string{
+						envVarName1: envVarValue1,
+						envVarName2: envVarValue2,
+					},
+				},
+			},
+			outFile: "basemanifest-output-addcontainer.json",
+		},
+	}
+
+	for _, tc := range manifestTests {
+		t.Run(tc.name, func(t *testing.T) {
+			inYAML := testutil.ReadFixture(tc.inFile)
+			tc.container.Runtimes = &datamodel.RuntimeProperties{
+				Kubernetes: &datamodel.KubernetesRuntime{
+					Base: string(inYAML),
+				},
+			}
+
+			resource := makeResource(t, tc.container)
+			dependencies := map[string]renderers.RendererDependency{}
+
+			ctx := testcontext.New(t)
+			renderer := Renderer{}
+			output, err := renderer.Render(ctx, resource, renderers.RenderOptions{Dependencies: dependencies})
+			require.NoError(t, err)
+
+			deployment, _ := kubernetes.FindDeployment(output.Resources)
+			require.NotNil(t, deployment)
+
+			actual, err := json.MarshalIndent(deployment, "", "  ")
+			require.NoError(t, err)
+
+			outputYaml := testutil.ReadFixture(tc.outFile)
+			require.Equal(t, string(outputYaml), string(actual), "actual output: %s", string(actual))
+		})
+	}
+}
+
 func renderOptionsEnvAndAppKubeMetadata() renderers.RenderOptions {
 	dependencies := map[string]renderers.RendererDependency{}
 	option := renderers.RenderOptions{Dependencies: dependencies}
diff --git a/pkg/corerp/renderers/container/testdata/basemanifest-input-addcontainer.yaml b/pkg/corerp/renderers/container/testdata/basemanifest-input-addcontainer.yaml
new file mode 100644
index 0000000000..54c8196aa9
--- /dev/null
+++ b/pkg/corerp/renderers/container/testdata/basemanifest-input-addcontainer.yaml
@@ -0,0 +1,25 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test-container
+  labels:
+    app: test-container
+  annotations:
+    source: base-manifest-test
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: test-container
+      basemanifest: default
+  template:
+    spec:
+      containers:
+        - name: sidecar
+          image: "sidecar:latest"
+          ports:
+          - containerPort: 80
+            protocol: TCP
+          env:
+          - name: KEY
+            value: VALUE
diff --git a/pkg/corerp/renderers/container/testdata/basemanifest-input-merge.yaml b/pkg/corerp/renderers/container/testdata/basemanifest-input-merge.yaml
new file mode 100644
index 0000000000..21fe452104
--- /dev/null
+++ b/pkg/corerp/renderers/container/testdata/basemanifest-input-merge.yaml
@@ -0,0 +1,95 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: test-container
+  labels:
+    app: test-container
+  annotations:
+    source: base-manifest-test
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app: test-container
+      basemanifest: default
+  template:
+    metadata:
+      labels:
+        app: test-container
+        basemanifest: default
+    spec:
+      serviceAccountName: test-container
+      volumes:
+        - name: secret-vol
+          secret:
+            secretName: test-container-secret0
+      containers:
+        - name: test-container
+          ports:
+          - containerPort: 80
+            protocol: TCP
+          volumeMounts:
+          - name: secret-vol
+            readOnly: true
+            mountPath: /etc/secret-vol
+          env:
+          - name: TEST_SECRET_KEY
+            valueFrom:
+              secretKeyRef:
+                name: test-container-secret1
+                key: secret1
+          - name: TEST_CONFIGMAP_KEY
+            valueFrom:
+              configMapKeyRef:
+                name: test-container-config
+                key: TEST_CONFIGMAP
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: test-container
+  annotations:
+    source: base-manifest-test
+spec:
+  selector:
+    app.kubernetes.io/name: test-container
+  ports:
+    - protocol: TCP
+      port: 3000
+      targetPort: 3000
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: test-container
+  annotations:
+    source: base-manifest-test
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: test-container-secret0
+  annotations:
+    source: base-manifest-test
+type: Opaque
+stringData:
+  'secret0': test-secret-0
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: test-container-secret1
+  annotations:
+    source: base-manifest-test
+type: Opaque
+stringData:
+  'secret1': test-secret-1
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: test-container-config
+  annotations:
+    source: base-manifest-test
+data:
+  TEST_CONFIGMAP: test-configmap
diff --git a/pkg/corerp/renderers/container/testdata/basemanifest-output-addcontainer.json b/pkg/corerp/renderers/container/testdata/basemanifest-output-addcontainer.json
new file mode 100644
index 0000000000..68a684b94d
--- /dev/null
+++ b/pkg/corerp/renderers/container/testdata/basemanifest-output-addcontainer.json
@@ -0,0 +1,84 @@
+{
+  "kind": "Deployment",
+  "apiVersion": "apps/v1",
+  "metadata": {
+    "name": "test-container",
+    "creationTimestamp": null,
+    "labels": {
+      "app": "test-container",
+      "app.kubernetes.io/managed-by": "radius-rp",
+      "app.kubernetes.io/name": "test-container",
+      "app.kubernetes.io/part-of": "test-app",
+      "radius.dev/application": "test-app",
+      "radius.dev/resource": "test-container",
+      "radius.dev/resource-type": "applications.core-containers"
+    },
+    "annotations": {
+      "source": "base-manifest-test"
+    }
+  },
+  "spec": {
+    "replicas": 3,
+    "selector": {
+      "matchLabels": {
+        "app": "test-container",
+        "basemanifest": "default",
+        "radius.dev/application": "test-app",
+        "radius.dev/resource": "test-container"
+      }
+    },
+    "template": {
+      "metadata": {
+        "creationTimestamp": null,
+        "labels": {
+          "app.kubernetes.io/managed-by": "radius-rp",
+          "app.kubernetes.io/name": "test-container",
+          "app.kubernetes.io/part-of": "test-app",
+          "radius.dev/application": "test-app",
+          "radius.dev/resource": "test-container",
+          "radius.dev/resource-type": "applications.core-containers"
+        }
+      },
+      "spec": {
+        "containers": [
+          {
+            "name": "sidecar",
+            "image": "sidecar:latest",
+            "ports": [
+              {
+                "containerPort": 80,
+                "protocol": "TCP"
+              }
+            ],
+            "env": [
+              {
+                "name": "KEY",
+                "value": "VALUE"
+              }
+            ],
+            "resources": {}
+          },
+          {
+            "name": "test-container",
+            "image": "someimage:latest",
+            "env": [
+              {
+                "name": "TEST_VAR_1",
+                "value": "TEST_VALUE_1"
+              },
+              {
+                "name": "TEST_VAR_2",
+                "value": "81"
+              }
+            ],
+            "resources": {}
+          }
+        ],
+        "serviceAccountName": "test-container",
+        "enableServiceLinks": false
+      }
+    },
+    "strategy": {}
+  },
+  "status": {}
+}
\ No newline at end of file
diff --git a/pkg/corerp/renderers/container/testdata/basemanifest-output-merge.json b/pkg/corerp/renderers/container/testdata/basemanifest-output-merge.json
new file mode 100644
index 0000000000..2fdd583332
--- /dev/null
+++ b/pkg/corerp/renderers/container/testdata/basemanifest-output-merge.json
@@ -0,0 +1,118 @@
+{
+  "kind": "Deployment",
+  "apiVersion": "apps/v1",
+  "metadata": {
+    "name": "test-container",
+    "creationTimestamp": null,
+    "labels": {
+      "app": "test-container",
+      "app.kubernetes.io/managed-by": "radius-rp",
+      "app.kubernetes.io/name": "test-container",
+      "app.kubernetes.io/part-of": "test-app",
+      "radius.dev/application": "test-app",
+      "radius.dev/resource": "test-container",
+      "radius.dev/resource-type": "applications.core-containers"
+    },
+    "annotations": {
+      "source": "base-manifest-test"
+    }
+  },
+  "spec": {
+    "replicas": 3,
+    "selector": {
+      "matchLabels": {
+        "app": "test-container",
+        "basemanifest": "default",
+        "radius.dev/application": "test-app",
+        "radius.dev/resource": "test-container"
+      }
+    },
+    "template": {
+      "metadata": {
+        "creationTimestamp": null,
+        "labels": {
+          "app": "test-container",
+          "app.kubernetes.io/managed-by": "radius-rp",
+          "app.kubernetes.io/name": "test-container",
+          "app.kubernetes.io/part-of": "test-app",
+          "basemanifest": "default",
+          "radius.dev/application": "test-app",
+          "radius.dev/resource": "test-container",
+          "radius.dev/resource-type": "applications.core-containers"
+        }
+      },
+      "spec": {
+        "volumes": [
+          {
+            "name": "secret-vol",
+            "secret": {
+              "secretName": "test-container-secret0"
+            }
+          },
+          {
+            "name": "ephemeralVolume",
+            "emptyDir": {
+              "medium": "Memory"
+            }
+          }
+        ],
+        "containers": [
+          {
+            "name": "test-container",
+            "image": "someimage:latest",
+            "ports": [
+              {
+                "containerPort": 80,
+                "protocol": "TCP"
+              }
+            ],
+            "env": [
+              {
+                "name": "TEST_SECRET_KEY",
+                "valueFrom": {
+                  "secretKeyRef": {
+                    "name": "test-container-secret1",
+                    "key": "secret1"
+                  }
+                }
+              },
+              {
+                "name": "TEST_CONFIGMAP_KEY",
+                "valueFrom": {
+                  "configMapKeyRef": {
+                    "name": "test-container-config",
+                    "key": "TEST_CONFIGMAP"
+                  }
+                }
+              },
+              {
+                "name": "TEST_VAR_1",
+                "value": "TEST_VALUE_1"
+              },
+              {
+                "name": "TEST_VAR_2",
+                "value": "81"
+              }
+            ],
+            "resources": {},
+            "volumeMounts": [
+              {
+                "name": "secret-vol",
+                "readOnly": true,
+                "mountPath": "/etc/secret-vol"
+              },
+              {
+                "name": "ephemeralVolume",
+                "mountPath": "/mnt/ephemeral"
+              }
+            ]
+          }
+        ],
+        "serviceAccountName": "test-container",
+        "enableServiceLinks": false
+      }
+    },
+    "strategy": {}
+  },
+  "status": {}
+}
\ No newline at end of file