diff --git a/libs/core/langchain_core/_api/deprecation.py b/libs/core/langchain_core/_api/deprecation.py
index 16a540b860c..ccc31d6b9a5 100644
--- a/libs/core/langchain_core/_api/deprecation.py
+++ b/libs/core/langchain_core/_api/deprecation.py
@@ -12,20 +12,39 @@ module.
 import contextlib
 import functools
 import inspect
+import sys
 import warnings
 from collections.abc import Callable, Generator
 from typing import (
+    TYPE_CHECKING,
     Any,
     ParamSpec,
+    TypeGuard,
     TypeVar,
     cast,
 )
 
 from pydantic.fields import FieldInfo
-from pydantic.v1.fields import FieldInfo as FieldInfoV1
 
 from langchain_core._api.internal import is_caller_internal
 
+if TYPE_CHECKING:
+    from pydantic.v1.fields import FieldInfo as FieldInfoV1
+
+
+def _is_pydantic_v1_field_info(obj: Any) -> TypeGuard["FieldInfoV1"]:
+    """Check if `obj` is a `pydantic.v1.fields.FieldInfo` without forcing import.
+
+    Importing `pydantic.v1` emits a `UserWarning` on Python 3.14+. Skipping the
+    import entirely when no caller has constructed a v1 `FieldInfo` keeps that
+    warning out of `langchain_core`'s import path. If a caller did construct one,
+    `pydantic.v1.fields` is already in `sys.modules` and isinstance is safe.
+    """
+    mod = sys.modules.get("pydantic.v1.fields")
+    if mod is None:
+        return False
+    return isinstance(obj, mod.FieldInfo)
+
 
 def _build_deprecation_message(
     *,
@@ -59,7 +78,9 @@ class LangChainPendingDeprecationWarning(PendingDeprecationWarning):
 # PUBLIC API
 
 
-# Last Any should be FieldInfoV1 but this leads to circular imports
+# Bound is `Any` (not `FieldInfoV1`) because importing `pydantic.v1` at module
+# scope emits a `UserWarning` on Python 3.14+; v1 `FieldInfo` support is handled
+# at runtime via `_is_pydantic_v1_field_info`.
 T = TypeVar("T", bound=type | Callable[..., Any] | Any)
 
 
@@ -246,7 +267,7 @@ def deprecated(
                 )
                 return obj
 
-        elif isinstance(obj, FieldInfoV1):
+        elif _is_pydantic_v1_field_info(obj):
             wrapped = None
             if not _obj_type:
                 _obj_type = "attribute"
@@ -256,6 +277,8 @@ def deprecated(
             old_doc = obj.description
 
             def finalize(_: Callable[..., Any], new_doc: str, /) -> T:
+                from pydantic.v1.fields import FieldInfo as FieldInfoV1  # noqa: PLC0415
+
                 return cast(
                     "T",
                     FieldInfoV1(
diff --git a/libs/core/tests/unit_tests/_api/test_deprecation.py b/libs/core/tests/unit_tests/_api/test_deprecation.py
index c3aac854209..7993a823380 100644
--- a/libs/core/tests/unit_tests/_api/test_deprecation.py
+++ b/libs/core/tests/unit_tests/_api/test_deprecation.py
@@ -1,4 +1,6 @@
 import inspect
+import subprocess
+import sys
 import warnings
 from typing import Any
 
@@ -588,3 +590,43 @@ def test_deprecated_property_has_pep702_attribute() -> None:
     # The __deprecated__ attribute is on the underlying fget function
     assert hasattr(prop.fget, "__deprecated__")
     assert prop.fget.__deprecated__ == "Use new_property instead."
+
+
+def test_importing_deprecation_does_not_load_pydantic_v1() -> None:
+    """`langchain_core._api.deprecation` must not eagerly import `pydantic.v1`.
+
+    Pydantic emits a `UserWarning` from `pydantic/v1/__init__.py` on Python 3.14+,
+    and the module is on the import path for much of `langchain_core`. Run in a
+    fresh subprocess because sibling tests in this process may have already
+    imported `pydantic.v1` transitively.
+    """
+    code = (
+        "import sys\n"
+        "import langchain_core._api.deprecation  # noqa: F401\n"
+        "loaded = sorted(m for m in sys.modules if m.startswith('pydantic.v1'))\n"
+        "assert not loaded, loaded\n"
+    )
+    subprocess.run([sys.executable, "-c", code], check=True)
+
+
+def test_deprecated_pydantic_v1_field_info() -> None:
+    """The lazy v1 `FieldInfo` branch wraps and reconstructs the field correctly.
+
+    Verifies behavior when `pydantic.v1` is loaded by the caller.
+    """
+    from pydantic.v1 import BaseModel as V1Base  # noqa: PLC0415
+    from pydantic.v1.fields import FieldInfo as V1FieldInfo  # noqa: PLC0415
+
+    field = V1FieldInfo(default=1, description="original")
+    wrapped = deprecated(since="2.0.0", name="x", removal="3.0.0")(field)
+
+    assert isinstance(wrapped, V1FieldInfo)
+    assert wrapped.default == 1
+    assert "deprecated" in (wrapped.description or "").lower()
+    assert "original" in (wrapped.description or "")
+
+    # Sanity: still usable as a v1 model field.
+    class M(V1Base):
+        x: int = wrapped  # type: ignore[assignment]
+
+    assert M(x=2).x == 2