diff --git a/internal/client/client.go b/internal/client/client.go
index 9dde9516..1fcd2d4a 100644
--- a/internal/client/client.go
+++ b/internal/client/client.go
@@ -97,6 +97,20 @@ type CSAPI struct {
 	txnID int64
 }
 
+// CreateMedia creates an MXC URI for asynchronous media uploads.
+func (c *CSAPI) CreateMedia(t *testing.T) string {
+	t.Helper()
+	res := c.MustDoFunc(t, "POST", []string{"_matrix", "media", "v1", "create"})
+	body := ParseJSON(t, res)
+	return GetJSONFieldStr(t, body, "content_uri")
+}
+
+// UploadMediaAsync uploads the provided content to the given server and media ID. Fails the test on error.
+func (c *CSAPI) UploadMediaAsync(t *testing.T, serverName, mediaID string, fileBody []byte, fileName string, contentType string) {
+	t.Helper()
+	c.MustDoFunc(t, "PUT", []string{"_matrix", "media", "v3", "upload", serverName, mediaID})
+}
+
 // UploadContent uploads the provided content with an optional file name. Fails the test on error. Returns the MXC URI.
 func (c *CSAPI) UploadContent(t *testing.T, fileBody []byte, fileName string, contentType string) string {
 	t.Helper()
diff --git a/tests/csapi/media_async_uploads_test.go b/tests/csapi/media_async_uploads_test.go
new file mode 100644
index 00000000..3c235b5e
--- /dev/null
+++ b/tests/csapi/media_async_uploads_test.go
@@ -0,0 +1,46 @@
+package csapi_tests
+
+import (
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/matrix-org/complement/internal/b"
+	"github.com/matrix-org/complement/internal/client"
+	"github.com/matrix-org/complement/internal/data"
+	"github.com/matrix-org/complement/runtime"
+)
+
+func TestAsyncUpload(t *testing.T) {
+	runtime.SkipIf(t, runtime.Dendrite) // Dendrite doesn't support async uploads
+
+	deployment := Deploy(t, b.BlueprintAlice)
+	defer deployment.Destroy(t)
+
+	alice := deployment.Client(t, "hs1", "@alice:hs1")
+
+	var mxcURI, mediaID string
+	t.Run("Create media", func(t *testing.T) {
+		mxcURI = alice.CreateMedia(t)
+		parts := strings.Split(mxcURI, "/")
+		mediaID = parts[len(parts)-1]
+	})
+
+	origin, mediaID := client.SplitMxc(mxcURI)
+
+	t.Run("Not yet uploaded", func(t *testing.T) {
+		// Check that the media is not yet uploaded
+		res := alice.DoFunc(t, "GET", []string{"_matrix", "media", "v3", "download", origin, mediaID})
+		if res.StatusCode != http.StatusGatewayTimeout {
+			t.Fatalf("Expected 504 response code, got %d", res.StatusCode)
+		}
+	})
+
+	t.Run("Upload media", func(t *testing.T) {
+		alice.UploadMediaAsync(t, origin, mediaID, data.MatrixPng, "test.png", "image/png")
+	})
+
+	t.Run("Cannot upload to a media ID that has already been uploaded to", func(t *testing.T) {
+		alice.UploadMediaAsync(t, origin, mediaID, data.MatrixPng, "test.png", "image/png")
+	})
+}