diff --git a/sqlmodel/_compat.py b/sqlmodel/_compat.py
index a220b193f1..e1075387e7 100644
--- a/sqlmodel/_compat.py
+++ b/sqlmodel/_compat.py
@@ -320,7 +320,13 @@ def sqlmodel_validate(
     # Get and set any relationship objects
     if is_table_model_class(cls):
         for key in new_obj.__sqlmodel_relationships__:
-            value = getattr(use_obj, key, Undefined)
+            # use_obj can be a dict (the input obj, or the merged obj when
+            # update is passed), so read relationships accordingly instead of
+            # assuming attribute access.
+            if isinstance(use_obj, dict):
+                value = use_obj.get(key, Undefined)
+            else:
+                value = getattr(use_obj, key, Undefined)
             if value is not Undefined:
                 setattr(new_obj, key, value)
     return new_obj
diff --git a/tests/test_validation.py b/tests/test_validation.py
index 47fbca87c2..cc8f27c74c 100644
--- a/tests/test_validation.py
+++ b/tests/test_validation.py
@@ -29,3 +29,28 @@ def reject_none(cls, v):
 
     with pytest.raises(ValidationError):
         Hero.model_validate({"name": None, "age": 25})
+
+
+def test_validate_dict_sets_relationship(clear_sqlmodel):
+    """A relationship passed inside the dict given to model_validate must be
+    set, consistent with the constructor and with model_validate(object)."""
+
+    from sqlmodel import Field, Relationship
+
+    class Team(SQLModel, table=True):
+        id: int | None = Field(default=None, primary_key=True)
+        name: str
+        heroes: list["Hero"] = Relationship(back_populates="team")
+
+    class Hero(SQLModel, table=True):
+        id: int | None = Field(default=None, primary_key=True)
+        name: str
+        team_id: int | None = Field(default=None, foreign_key="team.id")
+        team: Team | None = Relationship(back_populates="heroes")
+
+    team = Team(name="Avengers")
+
+    # constructor already works; model_validate must match it
+    assert Hero(name="IronMan", team=team).team is team
+    assert Hero.model_validate({"name": "Thor", "team": team}).team is team
+    assert Hero.model_validate({"name": "Hulk"}, update={"team": team}).team is team