diff --git a/src/WebformCivicrmPreProcess.php b/src/WebformCivicrmPreProcess.php
index 6364c89a4..8b8831af0 100644
--- a/src/WebformCivicrmPreProcess.php
+++ b/src/WebformCivicrmPreProcess.php
@@ -781,8 +781,15 @@ private function findExistingActivities() {
                 'is_deleted' => '0',
                 'is_current_revision' => '1',
                 'options' => ['limit' => 1],
+                'activity_type_id' => $this->data['activity'][$n]['activity'][1]['activity_type_id'],
               ];
-              $params['activity_type_id'] = $this->data['activity'][$n]['activity'][1]['activity_type_id'];
+              $caseType = $this->data['activity'][$n]['case_type_id'] ?? NULL;
+              if (!empty($caseType) && $caseType[0] === '#') {
+                $case_num = substr($caseType, 1);
+                if (!empty($this->ent['case'][$case_num]['id'])) {
+                  $params['case_id'] = $this->ent['case'][$case_num]['id'];
+                }
+              }
               $items = $this->utils->wf_crm_apivalues('activity', 'get', $params);
               if (isset($items[0]['id'])) {
                 $this->ent['activity'][$n] = ['id' => $items[0]['id']];
diff --git a/tests/src/FunctionalJavascript/CaseSubmissionTest.php b/tests/src/FunctionalJavascript/CaseSubmissionTest.php
index 850ce2756..c98622878 100644
--- a/tests/src/FunctionalJavascript/CaseSubmissionTest.php
+++ b/tests/src/FunctionalJavascript/CaseSubmissionTest.php
@@ -30,9 +30,70 @@ protected function setUp(): void {
     $this->getSession()->getPage()->checkField('Case Subject');
     $this->getSession()->getPage()->checkField('Case Start Date');
 
+    // Configure Activity Tab
+    $this->getSession()->getPage()->clickLink('Activities');
+    $this->getSession()->getPage()->selectFieldOption('activity_number_of_activity', 1);
+    $this->assertSession()->waitForField('civicrm_1_activity_1_activity_subject');
+    $this->htmlOutput();
+    $this->getSession()->getPage()->selectFieldOption('Update Existing Activity', 'Scheduled');
+    $this->getSession()->getPage()->selectFieldOption('File On Case', 'Case 1');
+    $this->assertSession()->assertWaitOnAjaxRequest();
+
+    $this->getSession()->getPage()->checkField('Activity Subject');
+    $this->getSession()->getPage()->selectFieldOption('Activity Type', 'Follow up');
+    $this->assertSession()->assertWaitOnAjaxRequest();
+
     $this->saveCiviCRMSettings();
   }
 
+  /**
+   * Verify correct Case and related Activity
+   * is loaded on the webform by default.
+   */
+  public function testCaseActivityDefaults() {
+    $cases = [
+      [
+        'subject' => 'Case 1 subject',
+        'status' => 'Closed',
+        'activity_subject' => 'Followup Activity from Case 1',
+      ],
+      [
+        'subject' => 'Case 2 subject',
+        'status' => 'Open',
+        'activity_subject' => 'Followup Activity from Case 2',
+      ],
+    ];
+    // Create case 1 with status=Resolved
+    // Create case 2 with status=Ongoing
+    foreach ($cases as $params) {
+      $case = \Civi\Api4\CiviCase::create(TRUE)
+        ->addValue('case_type_id.name', 'housing_support')
+        ->addValue('status_id:name', $params['status'])
+        ->addValue('contact_id', $this->rootUserCid)
+        ->addValue('subject', $params['subject'])
+        ->addValue('creator_id', $this->rootUserCid)
+        ->execute()
+        ->first();
+
+      // Add subject to the followup activity
+      \Civi\Api4\Activity::update(TRUE)
+        ->addValue('subject', $params['activity_subject'])
+        ->addWhere('case_id', '=',  $case['id'])
+        ->addWhere('activity_type_id:name', '=', 'Follow up')
+        ->execute()
+        ->first();
+    }
+
+    // Load the webform
+    $this->drupalGet($this->webform->toUrl('canonical'));
+    $this->htmlOutput();
+    $this->assertPageNoErrorMessages();
+
+    // Ensure case subject and activity subject is populated correctly.
+    $this->assertSession()->fieldValueEquals('civicrm_1_case_1_case_subject', 'Case 2 subject');
+    $this->assertSession()->fieldValueEquals('civicrm_1_activity_1_activity_subject', 'Followup Activity from Case 2');
+  }
+
   /**
    * Test Case Submission.
    */