diff --git a/client/src/entrypoints/admin/page-chooser-telepath.js b/client/src/entrypoints/admin/page-chooser-telepath.js
index 4f9cd699dc..769a33590a 100644
--- a/client/src/entrypoints/admin/page-chooser-telepath.js
+++ b/client/src/entrypoints/admin/page-chooser-telepath.js
@@ -11,7 +11,7 @@ class PageChooserFactory {
     placeholder.outerHTML = html;
     /* the PageChooser object also serves as the JS widget representation */
     // eslint-disable-next-line no-undef
-    const chooser = new PageChooser(id, null, this.config);
+    const chooser = new PageChooser(id, this.config);
     chooser.setState(initialState);
     return chooser;
   }
diff --git a/client/src/entrypoints/admin/page-chooser.js b/client/src/entrypoints/admin/page-chooser.js
index de1424518a..9d6b3993be 100644
--- a/client/src/entrypoints/admin/page-chooser.js
+++ b/client/src/entrypoints/admin/page-chooser.js
@@ -7,27 +7,33 @@ class PageChooser extends Chooser {
   titleStateKey = 'adminTitle';
   editUrlStateKey = 'editUrl';
 
-  constructor(id, parentId, options = {}) {
-    super(id);
-    this.initialParentId = parentId;
-    this.options = options;
+  constructor(id, arg1, arg2) {
+    let opts;
+    if (arg2 || typeof arg1 === 'number') {
+      /* old-style args: (id, parentId, opts) */
+      opts = { parent_id: arg1, ...arg2 };
+    } else {
+      /* new style args: (id, opts) where opts includes 'parent_id' */
+      opts = arg1 || {};
+    }
+    super(id, opts);
   }
 
   getStateFromHTML() {
     const state = super.getStateFromHTML();
     if (state) {
-      state.parentId = this.initialParentId;
+      state.parentId = this.opts.parent_id;
     }
     return state;
   }
 
   getModalOptions() {
     const opts = {
-      model_names: this.options.model_names,
-      target_pages: this.options.target_pages,
-      match_subclass: this.options.match_subclass,
-      can_choose_root: this.options.can_choose_root,
-      user_perms: this.options.user_perms,
+      model_names: this.opts.model_names,
+      target_pages: this.opts.target_pages,
+      match_subclass: this.opts.match_subclass,
+      can_choose_root: this.opts.can_choose_root,
+      user_perms: this.opts.user_perms,
     };
     if (this.state && this.state.parentId) {
       opts.parentId = this.state.parentId;
diff --git a/wagtail/admin/tests/test_edit_handlers.py b/wagtail/admin/tests/test_edit_handlers.py
index 80d13039da..cdd148f5f3 100644
--- a/wagtail/admin/tests/test_edit_handlers.py
+++ b/wagtail/admin/tests/test_edit_handlers.py
@@ -947,7 +947,7 @@ class TestPageChooserPanel(TestCase):
 
     def test_render_js_init(self):
         result = self.page_chooser_panel.render_html()
-        expected_js = 'new PageChooser("{id}", {parent}, {{"model_names": ["{model}"], "can_choose_root": false, "user_perms": null}});'.format(
+        expected_js = 'new PageChooser("{id}", {{"model_names": ["{model}"], "can_choose_root": false, "user_perms": null, "parent_id": {parent}}});'.format(
             id="id_page", model="wagtailcore.page", parent=self.events_index_page.id
         )
 
@@ -969,7 +969,7 @@ class TestPageChooserPanel(TestCase):
         result = page_chooser_panel.render_html()
 
         # the canChooseRoot flag on PageChooser should now be true
-        expected_js = 'new PageChooser("{id}", {parent}, {{"model_names": ["{model}"], "can_choose_root": true, "user_perms": null}});'.format(
+        expected_js = 'new PageChooser("{id}", {{"model_names": ["{model}"], "can_choose_root": true, "user_perms": null, "parent_id": {parent}}});'.format(
             id="id_page", model="wagtailcore.page", parent=self.events_index_page.id
         )
         self.assertIn(expected_js, result)
@@ -1025,7 +1025,7 @@ class TestPageChooserPanel(TestCase):
         )
 
         result = page_chooser_panel.render_html()
-        expected_js = 'new PageChooser("{id}", {parent}, {{"model_names": ["{model}"], "can_choose_root": false, "user_perms": null}});'.format(
+        expected_js = 'new PageChooser("{id}", {{"model_names": ["{model}"], "can_choose_root": false, "user_perms": null, "parent_id": {parent}}});'.format(
             id="id_page", model="tests.eventpage", parent=self.events_index_page.id
         )
 
@@ -1045,7 +1045,7 @@ class TestPageChooserPanel(TestCase):
         )
 
         result = page_chooser_panel.render_html()
-        expected_js = 'new PageChooser("{id}", {parent}, {{"model_names": ["{model}"], "can_choose_root": false, "user_perms": null}});'.format(
+        expected_js = 'new PageChooser("{id}", {{"model_names": ["{model}"], "can_choose_root": false, "user_perms": null, "parent_id": {parent}}});'.format(
             id="id_page", model="tests.eventpage", parent=self.events_index_page.id
         )
 
diff --git a/wagtail/admin/tests/test_widgets.py b/wagtail/admin/tests/test_widgets.py
index 56ed724826..97f1b3e720 100644
--- a/wagtail/admin/tests/test_widgets.py
+++ b/wagtail/admin/tests/test_widgets.py
@@ -73,7 +73,7 @@ class TestAdminPageChooserWidget(TestCase):
 
         html = widget.render("test", None, {"id": "test-id"})
         self.assertIn(
-            'new PageChooser("test-id", null, {"model_names": ["wagtailcore.page"], "can_choose_root": false, "user_perms": null});',
+            'new PageChooser("test-id", {"model_names": ["wagtailcore.page"], "can_choose_root": false, "user_perms": null});',
             html,
         )
 
@@ -82,7 +82,7 @@ class TestAdminPageChooserWidget(TestCase):
 
         html = widget.render("test", None, {"id": "test-id"})
         self.assertIn(
-            'new PageChooser("test-id", null, {"model_names": ["wagtailcore.page"], "can_choose_root": false, "user_perms": "copy_to"});',
+            'new PageChooser("test-id", {"model_names": ["wagtailcore.page"], "can_choose_root": false, "user_perms": "copy_to"});',
             html,
         )
 
@@ -99,7 +99,7 @@ class TestAdminPageChooserWidget(TestCase):
         self.assertInHTML("foobarbaz (simple page)", html)
 
         self.assertIn(
-            'new PageChooser("test-id", %d, {"model_names": ["wagtailcore.page"], "can_choose_root": false, "user_perms": null});'
+            'new PageChooser("test-id", {"model_names": ["wagtailcore.page"], "can_choose_root": false, "user_perms": null, "parent_id": %d});'
             % self.root_page.id,
             html,
         )
@@ -109,7 +109,7 @@ class TestAdminPageChooserWidget(TestCase):
 
         html = widget.render("test", None, {"id": "test-id"})
         self.assertIn(
-            'new PageChooser("test-id", null, {"model_names": ["tests.simplepage"], "can_choose_root": false, "user_perms": null});',
+            'new PageChooser("test-id", {"model_names": ["tests.simplepage"], "can_choose_root": false, "user_perms": null});',
             html,
         )
 
@@ -121,7 +121,7 @@ class TestAdminPageChooserWidget(TestCase):
 
         html = widget.render("test", None, {"id": "test-id"})
         self.assertIn(
-            'new PageChooser("test-id", null, {"model_names": ["tests.simplepage"], "can_choose_root": false, "user_perms": null});',
+            'new PageChooser("test-id", {"model_names": ["tests.simplepage"], "can_choose_root": false, "user_perms": null});',
             html,
         )
 
@@ -133,7 +133,7 @@ class TestAdminPageChooserWidget(TestCase):
 
         html = widget.render("test", None, {"id": "test-id"})
         self.assertIn(
-            'new PageChooser("test-id", null, {"model_names": ["tests.simplepage"], "can_choose_root": false, "user_perms": null});',
+            'new PageChooser("test-id", {"model_names": ["tests.simplepage"], "can_choose_root": false, "user_perms": null});',
             html,
         )
 
@@ -146,7 +146,7 @@ class TestAdminPageChooserWidget(TestCase):
 
         html = widget.render("test", None, {"id": "test-id"})
         self.assertIn(
-            'new PageChooser("test-id", null, {"model_names": ["tests.simplepage", "tests.eventpage"], "can_choose_root": false, "user_perms": null});',
+            'new PageChooser("test-id", {"model_names": ["tests.simplepage", "tests.eventpage"], "can_choose_root": false, "user_perms": null});',
             html,
         )
 
@@ -158,7 +158,7 @@ class TestAdminPageChooserWidget(TestCase):
 
         html = widget.render("test", self.child_page, {"id": "test-id"})
         self.assertIn(
-            'new PageChooser("test-id", %d, {"model_names": ["wagtailcore.page"], "can_choose_root": true, "user_perms": null});'
+            'new PageChooser("test-id", {"model_names": ["wagtailcore.page"], "can_choose_root": true, "user_perms": null, "parent_id": %d});'
             % self.root_page.id,
             html,
         )
diff --git a/wagtail/admin/widgets/chooser.py b/wagtail/admin/widgets/chooser.py
index 864c00297b..bd0ea13c00 100644
--- a/wagtail/admin/widgets/chooser.py
+++ b/wagtail/admin/widgets/chooser.py
@@ -344,10 +344,13 @@ class AdminPageChooser(BaseChooser):
 
     def render_js_init(self, id_, name, value_data):
         value_data = value_data or {}
-        return "new PageChooser({id}, {parent}, {options});".format(
+        options = self.client_options
+        parent_id = value_data.get("parent_id")
+        if parent_id is not None:
+            options["parent_id"] = parent_id
+        return "new PageChooser({id}, {options});".format(
             id=json.dumps(id_),
-            parent=json.dumps(value_data.get("parent_id")),
-            options=json.dumps(self.client_options),
+            options=json.dumps(options),
         )
 
     @property