diff --git a/wagtail/core/blocks/list_block.py b/wagtail/core/blocks/list_block.py
index 4d08065f32..9c9f80a8cb 100644
--- a/wagtail/core/blocks/list_block.py
+++ b/wagtail/core/blocks/list_block.py
@@ -146,9 +146,11 @@ class ListBlock(Block):
         result = []
         errors = []
         non_block_errors = ErrorList()
-        for child_val in value:
+        for bound_block in value.bound_blocks:
             try:
-                result.append(self.child_block.clean(child_val))
+                result.append(ListValue.ListChild(
+                    self.child_block, self.child_block.clean(bound_block.value), id=bound_block.id
+                ))
             except ValidationError as e:
                 errors.append(ErrorList([e]))
             else:
@@ -167,7 +169,7 @@ class ListBlock(Block):
         if any(errors) or non_block_errors:
             raise ListBlockValidationError(block_errors=errors, non_block_errors=non_block_errors)
 
-        return ListValue(self, values=result)
+        return ListValue(self, bound_blocks=result)
 
     def _item_is_in_block_format(self, item):
         # check a list item retrieved from the database JSON representation to see whether it follows
diff --git a/wagtail/core/tests/test_blocks.py b/wagtail/core/tests/test_blocks.py
index 7f17a25527..f2e2061928 100644
--- a/wagtail/core/tests/test_blocks.py
+++ b/wagtail/core/tests/test_blocks.py
@@ -2382,31 +2382,44 @@ class TestListBlock(WagtailTestUtils, SimpleTestCase):
             },
         })
 
+    def test_clean_preserves_block_ids(self):
+        block = blocks.ListBlock(blocks.CharBlock())
+        block_val = block.to_python([
+            {'type': 'item', 'value': 'foo', 'id': '11111111-1111-1111-1111-111111111111'},
+            {'type': 'item', 'value': 'bar', 'id': '22222222-2222-2222-2222-222222222222'},
+        ])
+        cleaned_block_val = block.clean(block_val)
+        self.assertEqual(cleaned_block_val.bound_blocks[0].id, '11111111-1111-1111-1111-111111111111')
+
     def test_min_num_validation_errors(self):
         block = blocks.ListBlock(blocks.CharBlock(), min_num=2)
+        block_val = block.to_python(['foo'])
 
         with self.assertRaises(ValidationError) as catcher:
-            block.clean(['foo'])
+            block.clean(block_val)
         self.assertEqual(catcher.exception.params, {
             'block_errors': [None],
             'non_block_errors': ['The minimum number of items is 2']
         })
 
         # a value with >= 2 blocks should pass validation
-        self.assertTrue(block.clean(['foo', 'bar']))
+        block_val = block.to_python(['foo', 'bar'])
+        self.assertTrue(block.clean(block_val))
 
     def test_max_num_validation_errors(self):
         block = blocks.ListBlock(blocks.CharBlock(), max_num=2)
+        block_val = block.to_python(['foo', 'bar', 'baz'])
 
         with self.assertRaises(ValidationError) as catcher:
-            block.clean(['foo', 'bar', 'baz'])
+            block.clean(block_val)
         self.assertEqual(catcher.exception.params, {
             'block_errors': [None, None, None],
             'non_block_errors': ['The maximum number of items is 2']
         })
 
         # a value with <= 2 blocks should pass validation
-        self.assertTrue(block.clean(['foo', 'bar']))
+        block_val = block.to_python(['foo', 'bar'])
+        self.assertTrue(block.clean(block_val))
 
     def test_unpack_old_database_format(self):
         block = blocks.ListBlock(blocks.CharBlock())