diff --git a/django/db/backends/base/schema.py b/django/db/backends/base/schema.py
index 76dea84cff..c8dc8e3a70 100644
--- a/django/db/backends/base/schema.py
+++ b/django/db/backends/base/schema.py
@@ -466,8 +466,10 @@ class BaseDatabaseSchemaEditor:
             if self.sql_create_column_inline_fk:
                 to_table = field.remote_field.model._meta.db_table
                 to_column = field.remote_field.model._meta.get_field(field.remote_field.field_name).column
+                namespace, _ = split_identifier(model._meta.db_table)
                 definition += " " + self.sql_create_column_inline_fk % {
                     'name': self._fk_constraint_name(model, field, constraint_suffix),
+                    'namespace': '%s.' % self.quote_name(namespace) if namespace else '',
                     'column': self.quote_name(field.column),
                     'to_table': self.quote_name(to_table),
                     'to_column': self.quote_name(to_column),
diff --git a/django/db/backends/postgresql/schema.py b/django/db/backends/postgresql/schema.py
index fbc4a59dc4..7687c37fe7 100644
--- a/django/db/backends/postgresql/schema.py
+++ b/django/db/backends/postgresql/schema.py
@@ -27,7 +27,7 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
     # transaction.
     sql_create_column_inline_fk = (
         'CONSTRAINT %(name)s REFERENCES %(to_table)s(%(to_column)s)%(deferrable)s'
-        '; SET CONSTRAINTS %(name)s IMMEDIATE'
+        '; SET CONSTRAINTS %(namespace)s%(name)s IMMEDIATE'
     )
     # Setting the constraint to IMMEDIATE runs any deferred checks to allow
     # dropping it in the same transaction.
diff --git a/docs/releases/3.0.8.txt b/docs/releases/3.0.8.txt
index 6bb3e39de7..f23208f9ae 100644
--- a/docs/releases/3.0.8.txt
+++ b/docs/releases/3.0.8.txt
@@ -18,3 +18,7 @@ Bugfixes
 * Reallowed, following a regression in Django 3.0, non-expressions having a
   ``filterable`` attribute to be used as the right-hand side in queryset
   filters (:ticket:`31664`).
+
+* Fixed a regression in Django 3.0.2 that caused a migration crash on
+  PostgreSQL when adding a foreign key to a model with a namespaced
+  ``db_table`` (:ticket:`31735`).
diff --git a/tests/schema/tests.py b/tests/schema/tests.py
index 5868d520e8..19b0a1dcc7 100644
--- a/tests/schema/tests.py
+++ b/tests/schema/tests.py
@@ -3060,6 +3060,35 @@ class SchemaTests(TransactionTestCase):
         student = Student.objects.create(name='Some man')
         doc.students.add(student)
 
+    @isolate_apps('schema')
+    @unittest.skipUnless(connection.vendor == 'postgresql', 'PostgreSQL specific db_table syntax.')
+    def test_namespaced_db_table_foreign_key_reference(self):
+        with connection.cursor() as cursor:
+            cursor.execute('CREATE SCHEMA django_schema_tests')
+
+        def delete_schema():
+            with connection.cursor() as cursor:
+                cursor.execute('DROP SCHEMA django_schema_tests CASCADE')
+
+        self.addCleanup(delete_schema)
+
+        class Author(Model):
+            class Meta:
+                app_label = 'schema'
+
+        class Book(Model):
+            class Meta:
+                app_label = 'schema'
+                db_table = '"django_schema_tests"."schema_book"'
+
+        author = ForeignKey(Author, CASCADE)
+        author.set_attributes_from_name('author')
+
+        with connection.schema_editor() as editor:
+            editor.create_model(Author)
+            editor.create_model(Book)
+            editor.add_field(Book, author)
+
     def test_rename_table_renames_deferred_sql_references(self):
         atomic_rename = connection.features.supports_atomic_references_rename
         with connection.schema_editor(atomic=atomic_rename) as editor: