diff --git a/backend/app/alembic/versions/v0_16_4_migration.py b/backend/app/alembic/versions/v0_16_4_migration.py
index 77c62d672..caea9122e 100644
--- a/backend/app/alembic/versions/v0_16_4_migration.py
+++ b/backend/app/alembic/versions/v0_16_4_migration.py
@@ -94,10 +94,12 @@ def upgrade() -> None:
         sa.ForeignKeyConstraint(
             ["idp_id"],
             ["identity_providers.id"],
+            ondelete="CASCADE",
         ),
         sa.ForeignKeyConstraint(
             ["user_id"],
             ["users.id"],
+            ondelete="CASCADE",
         ),
         sa.PrimaryKeyConstraint("id"),
     )
@@ -240,6 +242,7 @@ def upgrade() -> None:
         sa.ForeignKeyConstraint(
             ["token_family_id"],
             ["users_sessions.token_family_id"],
+            ondelete="CASCADE",
         ),
         sa.PrimaryKeyConstraint("id"),
         sa.UniqueConstraint("hashed_token"),
diff --git a/backend/app/auth/oauth_state/models.py b/backend/app/auth/oauth_state/models.py
index aacdbb718..02c83b962 100644
--- a/backend/app/auth/oauth_state/models.py
+++ b/backend/app/auth/oauth_state/models.py
@@ -42,7 +42,7 @@ class OAuthState(Base):
 
     idp_id = Column(
         Integer,
-        ForeignKey("identity_providers.id"),
+        ForeignKey("identity_providers.id", ondelete="CASCADE"),
         nullable=False,
         index=True,
         comment="Identity provider ID",
@@ -50,7 +50,7 @@ class OAuthState(Base):
 
     user_id = Column(
         Integer,
-        ForeignKey("users.id"),
+        ForeignKey("users.id", ondelete="CASCADE"),
         nullable=True,
         index=True,
         comment="User ID (for link mode)",
diff --git a/backend/app/session/rotated_refresh_tokens/models.py b/backend/app/session/rotated_refresh_tokens/models.py
index 79dfc8636..8bd936a97 100644
--- a/backend/app/session/rotated_refresh_tokens/models.py
+++ b/backend/app/session/rotated_refresh_tokens/models.py
@@ -28,7 +28,7 @@ class RotatedRefreshToken(Base):
     id = Column(Integer, primary_key=True, autoincrement=True)
     token_family_id = Column(
         String(36),
-        ForeignKey("users_sessions.token_family_id"),
+        ForeignKey("users_sessions.token_family_id", ondelete="CASCADE"),
         nullable=False,
         index=True,
         comment="UUID of the token family",