diff --git a/libs/core/langchain_core/pydantic_v1/__init__.py b/libs/core/langchain_core/pydantic_v1/__init__.py
index d17a0ac3a9e..6dfc11dc755 100644
--- a/libs/core/langchain_core/pydantic_v1/__init__.py
+++ b/libs/core/langchain_core/pydantic_v1/__init__.py
@@ -1,5 +1,7 @@
 from importlib import metadata
 
+from langchain_core._api.deprecation import warn_deprecated
+
 ## Create namespaces for pydantic v1 and v2.
 # This code must stay at the top of the file before other modules may
 # attempt to import pydantic since it adds pydantic_v1 and pydantic_v2 to sys.modules.
@@ -21,3 +23,21 @@ try:
     _PYDANTIC_MAJOR_VERSION: int = int(metadata.version("pydantic").split(".")[0])
 except metadata.PackageNotFoundError:
     _PYDANTIC_MAJOR_VERSION = 0
+
+warn_deprecated(
+    "0.3.0",
+    removal="1.0.0",
+    alternative="pydantic.v1 or pydantic",
+    message=(
+        "As of langchain-core 0.3.0, LangChain uses pydantic v2 internally. "
+        "The langchain_core.pydantic_v1 module was a "
+        "compatibility shim for pydantic v1, and should no longer be used. "
+        "Please update the code to import from Pydantic directly.\n\n"
+        "For example, replace imports like: "
+        "`from langchain_core.pydantic_v1 import BaseModel`\n"
+        "with: `from pydantic import BaseModel`\n"
+        "or the v1 compatibility namespace if you are working in a code base "
+        "that has not been fully upgraded to pydantic 2 yet. "
+        "\tfrom pydantic.v1 import BaseModel\n"
+    ),
+)
diff --git a/libs/core/langchain_core/pydantic_v1/dataclasses.py b/libs/core/langchain_core/pydantic_v1/dataclasses.py
index 2dfa3dab0aa..824da7d6b34 100644
--- a/libs/core/langchain_core/pydantic_v1/dataclasses.py
+++ b/libs/core/langchain_core/pydantic_v1/dataclasses.py
@@ -1,4 +1,24 @@
+from langchain_core._api import warn_deprecated
+
 try:
     from pydantic.v1.dataclasses import *  # noqa: F403
 except ImportError:
     from pydantic.dataclasses import *  # type: ignore # noqa: F403
+
+warn_deprecated(
+    "0.3.0",
+    removal="1.0.0",
+    alternative="pydantic.v1 or pydantic",
+    message=(
+        "As of langchain-core 0.3.0, LangChain uses pydantic v2 internally. "
+        "The langchain_core.pydantic_v1 module was a "
+        "compatibility shim for pydantic v1, and should no longer be used. "
+        "Please update the code to import from Pydantic directly.\n\n"
+        "For example, replace imports like: "
+        "`from langchain_core.pydantic_v1 import BaseModel`\n"
+        "with: `from pydantic import BaseModel`\n"
+        "or the v1 compatibility namespace if you are working in a code base "
+        "that has not been fully upgraded to pydantic 2 yet. "
+        "\tfrom pydantic.v1 import BaseModel\n"
+    ),
+)
diff --git a/libs/core/langchain_core/pydantic_v1/main.py b/libs/core/langchain_core/pydantic_v1/main.py
index fa8916f8350..3449832620e 100644
--- a/libs/core/langchain_core/pydantic_v1/main.py
+++ b/libs/core/langchain_core/pydantic_v1/main.py
@@ -1,4 +1,24 @@
+from langchain_core._api import warn_deprecated
+
 try:
     from pydantic.v1.main import *  # noqa: F403
 except ImportError:
     from pydantic.main import *  # type: ignore # noqa: F403
+
+warn_deprecated(
+    "0.3.0",
+    removal="1.0.0",
+    alternative="pydantic.v1 or pydantic",
+    message=(
+        "As of langchain-core 0.3.0, LangChain uses pydantic v2 internally. "
+        "The langchain_core.pydantic_v1 module was a "
+        "compatibility shim for pydantic v1, and should no longer be used. "
+        "Please update the code to import from Pydantic directly.\n\n"
+        "For example, replace imports like: "
+        "`from langchain_core.pydantic_v1 import BaseModel`\n"
+        "with: `from pydantic import BaseModel`\n"
+        "or the v1 compatibility namespace if you are working in a code base "
+        "that has not been fully upgraded to pydantic 2 yet. "
+        "\tfrom pydantic.v1 import BaseModel\n"
+    ),
+)
diff --git a/libs/langchain/langchain/pydantic_v1/__init__.py b/libs/langchain/langchain/pydantic_v1/__init__.py
index d17a0ac3a9e..c329193ffd3 100644
--- a/libs/langchain/langchain/pydantic_v1/__init__.py
+++ b/libs/langchain/langchain/pydantic_v1/__init__.py
@@ -1,5 +1,7 @@
 from importlib import metadata
 
+from langchain_core._api import warn_deprecated
+
 ## Create namespaces for pydantic v1 and v2.
 # This code must stay at the top of the file before other modules may
 # attempt to import pydantic since it adds pydantic_v1 and pydantic_v2 to sys.modules.
@@ -21,3 +23,21 @@ try:
     _PYDANTIC_MAJOR_VERSION: int = int(metadata.version("pydantic").split(".")[0])
 except metadata.PackageNotFoundError:
     _PYDANTIC_MAJOR_VERSION = 0
+
+warn_deprecated(
+    "0.3.0",
+    removal="1.0.0",
+    alternative="pydantic.v1 or pydantic",
+    message=(
+        "As of langchain-core 0.3.0, LangChain uses pydantic v2 internally. "
+        "The langchain.pydantic_v1 module was a "
+        "compatibility shim for pydantic v1, and should no longer be used. "
+        "Please update the code to import from Pydantic directly.\n\n"
+        "For example, replace imports like: "
+        "`from langchain.pydantic_v1 import BaseModel`\n"
+        "with: `from pydantic import BaseModel`\n"
+        "or the v1 compatibility namespace if you are working in a code base "
+        "that has not been fully upgraded to pydantic 2 yet. "
+        "\tfrom pydantic.v1 import BaseModel\n"
+    ),
+)
diff --git a/libs/langchain/langchain/pydantic_v1/dataclasses.py b/libs/langchain/langchain/pydantic_v1/dataclasses.py
index 2dfa3dab0aa..b057c5bb6cc 100644
--- a/libs/langchain/langchain/pydantic_v1/dataclasses.py
+++ b/libs/langchain/langchain/pydantic_v1/dataclasses.py
@@ -1,4 +1,24 @@
+from langchain_core._api import warn_deprecated
+
 try:
     from pydantic.v1.dataclasses import *  # noqa: F403
 except ImportError:
     from pydantic.dataclasses import *  # type: ignore # noqa: F403
+
+warn_deprecated(
+    "0.3.0",
+    removal="1.0.0",
+    alternative="pydantic.v1 or pydantic",
+    message=(
+        "As of langchain-core 0.3.0, LangChain uses pydantic v2 internally. "
+        "The langchain.pydantic_v1 module was a "
+        "compatibility shim for pydantic v1, and should no longer be used. "
+        "Please update the code to import from Pydantic directly.\n\n"
+        "For example, replace imports like: "
+        "`from langchain.pydantic_v1 import BaseModel`\n"
+        "with: `from pydantic import BaseModel`\n"
+        "or the v1 compatibility namespace if you are working in a code base "
+        "that has not been fully upgraded to pydantic 2 yet. "
+        "\tfrom pydantic.v1 import BaseModel\n"
+    ),
+)
diff --git a/libs/langchain/langchain/pydantic_v1/main.py b/libs/langchain/langchain/pydantic_v1/main.py
index fa8916f8350..d366b5a7ea4 100644
--- a/libs/langchain/langchain/pydantic_v1/main.py
+++ b/libs/langchain/langchain/pydantic_v1/main.py
@@ -1,4 +1,24 @@
+from langchain_core._api import warn_deprecated
+
 try:
     from pydantic.v1.main import *  # noqa: F403
 except ImportError:
     from pydantic.main import *  # type: ignore # noqa: F403
+
+warn_deprecated(
+    "0.3.0",
+    removal="1.0.0",
+    alternative="pydantic.v1 or pydantic",
+    message=(
+        "As of langchain-core 0.3.0, LangChain uses pydantic v2 internally. "
+        "The langchain.pydantic_v1 module was a "
+        "compatibility shim for pydantic v1, and should no longer be used. "
+        "Please update the code to import from Pydantic directly.\n\n"
+        "For example, replace imports like: "
+        "`from langchain.pydantic_v1 import BaseModel`\n"
+        "with: `from pydantic import BaseModel`\n"
+        "or the v1 compatibility namespace if you are working in a code base "
+        "that has not been fully upgraded to pydantic 2 yet. "
+        "\tfrom pydantic.v1 import BaseModel\n"
+    ),
+)