diff --git a/airflow/serialization/pydantic/dataset.py b/airflow/serialization/pydantic/dataset.py
index 096bda6ddd5d3..07d6b3bf88a2e 100644
--- a/airflow/serialization/pydantic/dataset.py
+++ b/airflow/serialization/pydantic/dataset.py
@@ -32,7 +32,6 @@ class Config:
         """Make sure it deals automatically with SQLAlchemy ORM classes."""
 
         from_attributes = True
-        orm_mode = True  # Pydantic 1.x compatibility.
 
 
 class TaskOutletDatasetReferencePydantic(BaseModelPydantic):
@@ -48,7 +47,6 @@ class Config:
         """Make sure it deals automatically with SQLAlchemy ORM classes."""
 
         from_attributes = True
-        orm_mode = True  # Pydantic 1.x compatibility.
 
 
 class DatasetPydantic(BaseModelPydantic):
@@ -68,7 +66,6 @@ class Config:
         """Make sure it deals automatically with SQLAlchemy ORM classes."""
 
         from_attributes = True
-        orm_mode = True  # Pydantic 1.x compatibility.
 
 
 class DatasetEventPydantic(BaseModelPydantic):
@@ -87,4 +84,3 @@ class Config:
         """Make sure it deals automatically with SQLAlchemy ORM classes."""
 
         from_attributes = True
-        orm_mode = True  # Pydantic 1.x compatibility.
diff --git a/airflow/serialization/pydantic/job.py b/airflow/serialization/pydantic/job.py
index 27c8ad8ca7496..5b0e961e04153 100644
--- a/airflow/serialization/pydantic/job.py
+++ b/airflow/serialization/pydantic/job.py
@@ -50,4 +50,3 @@ class Config:
         """Make sure it deals automatically with SQLAlchemy ORM classes."""
 
         from_attributes = True
-        orm_mode = True  # Pydantic 1.x compatibility.
diff --git a/airflow/serialization/pydantic/taskinstance.py b/airflow/serialization/pydantic/taskinstance.py
index 71d8ba576f11c..0bca3505cd8a1 100644
--- a/airflow/serialization/pydantic/taskinstance.py
+++ b/airflow/serialization/pydantic/taskinstance.py
@@ -61,7 +61,6 @@ class Config:
         """Make sure it deals automatically with SQLAlchemy ORM classes."""
 
         from_attributes = True
-        orm_mode = True  # Pydantic 1.x compatibility.
 
     def xcom_pull(
         self,
diff --git a/airflow/serialization/serialized_objects.py b/airflow/serialization/serialized_objects.py
index 67d08b7a94fd8..8e74788a7ae7a 100644
--- a/airflow/serialization/serialized_objects.py
+++ b/airflow/serialization/serialized_objects.py
@@ -485,10 +485,7 @@ def serialize(
         elif use_pydantic_models and _ENABLE_AIP_44:
 
             def _pydantic_model_dump(model_cls: type[BaseModel], var: Any) -> dict[str, Any]:
-                try:
-                    return model_cls.model_validate(var).model_dump()  # type: ignore[attr-defined]
-                except AttributeError:  # Pydantic 1.x compatibility.
-                    return model_cls.from_orm(var).dict()  # type: ignore[attr-defined]
+                return model_cls.model_validate(var).model_dump(mode="json")
 
             if isinstance(var, Job):
                 return cls._encode(_pydantic_model_dump(JobPydantic, var), type_=DAT.BASE_JOB)