diff --git a/src/Field/Configurator/AssociationConfigurator.php b/src/Field/Configurator/AssociationConfigurator.php
index c30b90b339..09e9603b7c 100644
--- a/src/Field/Configurator/AssociationConfigurator.php
+++ b/src/Field/Configurator/AssociationConfigurator.php
@@ -430,10 +430,20 @@ private function configureCrudForm(FieldDto $field, EntityDto $entityDto, string
             $crudPageName = Crud::PAGE_EDIT;
         }
 
-        $field->setFormTypeOption(
-            'entityDto',
-            $this->createEntityDto($targetEntityFqcn, $targetCrudControllerFqcn, $targetCrudControllerAction, $targetCrudControllerPageName, $crudPageName),
-        );
+        $embeddedEntityDto = $this->createEntityDto($targetEntityFqcn, $targetCrudControllerFqcn, $targetCrudControllerAction, $targetCrudControllerPageName, $crudPageName);
+        $field->setFormTypeOption('entityDto', $embeddedEntityDto);
+
+        // The assets declared by the embedded controller's fields (e.g. TextEditorField,
+        // FileField, a nested CollectionField...) live on the embedded EntityDto, not on
+        // the parent AssociationField. Propagate them up so that
+        // AbstractCrudController::getFieldAssets(), which only walks top-level fields,
+        // picks them up and outputs the required CSS/JS on the form page that hosts the
+        // embedded CRUD form. See #6127.
+        $assets = $field->getAssets();
+        foreach ($embeddedEntityDto->getFields() ?? [] as $embeddedField) {
+            $assets = $assets->mergeWith($embeddedField->getAssets());
+        }
+        $field->setAssets($assets);
     }
 
     /**
diff --git a/src/Field/Configurator/CollectionConfigurator.php b/src/Field/Configurator/CollectionConfigurator.php
index 5b9b47ebce..6add33a426 100644
--- a/src/Field/Configurator/CollectionConfigurator.php
+++ b/src/Field/Configurator/CollectionConfigurator.php
@@ -214,6 +214,19 @@ private function configureEntryType(FieldDto $fieldDto, EntityDto $entityDto, Ad
         $fieldDto->setFormTypeOption('prototype_options.entityDto', $newEntityDto);
         $fieldDto->setFormTypeOptionIfNotSet('prototype_data', $createEntryEntity());
         $fieldDto->setFormTypeOptionIfNotSet('entry_options.empty_data', $createEntryEntity);
+
+        // The assets declared by entry fields (e.g. TextEditorField, FileField, a nested
+        // CollectionField...) live on the entry EntityDto, not on the parent CollectionField.
+        // Propagate them up so that AbstractCrudController::getFieldAssets(), which only
+        // walks top-level fields, picks them up and outputs the required CSS/JS on the
+        // form page that hosts the embedded CRUD form. See #6127.
+        $assets = $fieldDto->getAssets();
+        foreach ([$editEntityDto, $newEntityDto] as $entryEntityDto) {
+            foreach ($entryEntityDto->getFields() ?? [] as $entryField) {
+                $assets = $assets->mergeWith($entryField->getAssets());
+            }
+        }
+        $fieldDto->setAssets($assets);
     }
 
     /**