diff --git a/pyproject.toml b/pyproject.toml
index 76c8526712..8398c63ec2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -43,7 +43,8 @@ dependencies = [
     "tenacity>=8.2.3",
     "pyroaring>=1.0.0",
     "cachetools>=5.5",
-    "zstandard>=0.13.0"
+    "zstandard>=0.13.0",
+    "typing-extensions>=4.4.0" # Self/override are imported at runtime on Python < 3.12
 ]
 
 [project.urls]
diff --git a/tests/test_version.py b/tests/test_version.py
index dcaa3f0735..1fa0c6a527 100644
--- a/tests/test_version.py
+++ b/tests/test_version.py
@@ -28,3 +28,22 @@ def test_version_format() -> None:
         "This failure could be due to a recent version bump in the Pyiceberg library. "
         "Please ensure you have the latest version installed by rerunning `make install` command."
     )
+
+
+def test_typing_extensions_is_a_core_dependency() -> None:
+    # typing_extensions is imported unconditionally at import time (e.g. Self in
+    # pyiceberg/typedef.py, override in the catalog and IO modules), so it must be a
+    # core runtime dependency rather than only a development one.
+    from importlib import metadata
+
+    from packaging.requirements import Requirement
+    from packaging.utils import canonicalize_name
+
+    requirements = [Requirement(requirement) for requirement in metadata.requires("pyiceberg") or []]
+    # Core dependencies carry no environment marker; optional extras add "; extra == ...".
+    core_dependencies = {canonicalize_name(requirement.name) for requirement in requirements if requirement.marker is None}
+
+    assert canonicalize_name("typing-extensions") in core_dependencies, (
+        "typing-extensions must be declared in [project.dependencies] because it is imported at runtime; "
+        "found only these core dependencies: " + ", ".join(sorted(core_dependencies))
+    )
diff --git a/uv.lock b/uv.lock
index 0aea046671..1b34be6687 100644
--- a/uv.lock
+++ b/uv.lock
@@ -1408,7 +1408,7 @@ name = "exceptiongroup"
 version = "1.3.1"
 source = { registry = "https://pypi.org/simple" }
 dependencies = [
-    { name = "typing-extensions", marker = "python_full_version < '3.13'" },
+    { name = "typing-extensions", marker = "python_full_version < '3.11'" },
 ]
 sdist = { url = "https://files.pythonhosted.org/packages/50/79/66800aadf48771f6b62f7eb014e352e5d06856655206165d775e675a02c9/exceptiongroup-1.3.1.tar.gz", hash = "sha256:8b412432c6055b0b7d14c310000ae93352ed6754f70fa8f7c34141f91c4e3219", size = 30371, upload-time = "2025-11-21T23:01:54.787Z" }
 wheels = [
@@ -4901,6 +4901,7 @@ dependencies = [
     { name = "rich" },
     { name = "strictyaml" },
     { name = "tenacity" },
+    { name = "typing-extensions" },
     { name = "zstandard" },
 ]
 
@@ -5078,6 +5079,7 @@ requires-dist = [
     { name = "thrift", marker = "extra == 'hive'", specifier = ">=0.13.0" },
     { name = "thrift", marker = "extra == 'hive-kerberos'", specifier = ">=0.13.0" },
     { name = "thrift-sasl", marker = "extra == 'hive-kerberos'", specifier = ">=0.4.3" },
+    { name = "typing-extensions", specifier = ">=4.4.0" },
     { name = "zstandard", specifier = ">=0.13.0" },
 ]
 provides-extras = ["pyarrow", "pandas", "duckdb", "ray", "bodo", "daft", "polars", "snappy", "hive", "hive-kerberos", "s3fs", "glue", "adlfs", "dynamodb", "bigquery", "sql-postgres", "sql-sqlite", "gcsfs", "rest-sigv4", "hf", "pyiceberg-core", "datafusion", "gcp-auth", "entra-auth", "geoarrow"]