diff --git a/ormar/fields/model_fields.py b/ormar/fields/model_fields.py
index ac1d534..9455f8d 100644
--- a/ormar/fields/model_fields.py
+++ b/ormar/fields/model_fields.py
@@ -91,7 +91,9 @@ class ModelFieldFactory:
             nullable, default, server_default, pydantic_only
         ) or is_auto_primary_key(primary_key, autoincrement)
         sql_nullable = (
-            nullable if sql_nullable is None else (sql_nullable and not primary_key)
+            False
+            if primary_key
+            else (nullable if sql_nullable is None else sql_nullable)
         )
 
         namespace = dict(
diff --git a/tests/test_model_definition/test_pk_field_is_always_not_null.py b/tests/test_model_definition/test_pk_field_is_always_not_null.py
new file mode 100644
index 0000000..22b03a3
--- /dev/null
+++ b/tests/test_model_definition/test_pk_field_is_always_not_null.py
@@ -0,0 +1,39 @@
+import databases
+import sqlalchemy
+
+import ormar
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL)
+metadata = sqlalchemy.MetaData()
+
+
+class BaseMeta(ormar.ModelMeta):
+    metadata = metadata
+    database = database
+
+
+class AutoincrementModel(ormar.Model):
+    class Meta(BaseMeta):
+        pass
+
+    id: int = ormar.Integer(primary_key=True)
+
+
+class NonAutoincrementModel(ormar.Model):
+    class Meta(BaseMeta):
+        pass
+
+    id: int = ormar.Integer(primary_key=True, autoincrement=False)
+
+
+class ExplicitNullableModel(ormar.Model):
+    class Meta(BaseMeta):
+        pass
+
+    id: int = ormar.Integer(primary_key=True, nullable=True)
+
+
+def test_pk_field_is_not_null():
+    for model in [AutoincrementModel, NonAutoincrementModel, ExplicitNullableModel]:
+        assert not model.Meta.table.c.get("id").nullable