diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8bd0a53c3c..0914929343 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- `opentelemetry-sdk`: Honour `OTEL_LOG_LEVEL` environment variable to configure the SDK's internal diagnostic logger; accepted values: `debug`, `info`, `warn`, `warning`, `error`, `critical`; invalid values emit a warning and default to `info`
+  ([#5115](https://github.com/open-telemetry/opentelemetry-python/issues/5115))
 - Fix incorrect code example in `create_tracer()` docstring
   ([#5072](https://github.com/open-telemetry/opentelemetry-python/issues/5072))
 - `opentelemetry-sdk`: add `load_entry_point` shared utility to declarative file configuration for loading plugins via entry points; refactor propagator loading to use it
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/__init__.py
new file mode 100644
index 0000000000..49da35917f
--- /dev/null
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/__init__.py
@@ -0,0 +1,47 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+The OpenTelemetry SDK package is an implementation of the OpenTelemetry API.
+"""
+
+import logging
+from os import environ
+
+from opentelemetry.sdk.environment_variables import OTEL_LOG_LEVEL
+
+# "warn" is accepted alongside "warning" because OTel canonical short names
+# use "WARN", so users following OTel documentation will naturally try "warn".
+_OTEL_LOG_LEVEL_TO_PYTHON = {
+    "debug": logging.DEBUG,
+    "info": logging.INFO,
+    "warn": logging.WARNING,
+    "warning": logging.WARNING,
+    "error": logging.ERROR,
+    "critical": logging.CRITICAL,
+}
+
+_otel_log_level_raw = environ.get(OTEL_LOG_LEVEL)
+if _otel_log_level_raw:
+    _logger = logging.getLogger(__name__)
+    _otel_log_level = _otel_log_level_raw.lower()
+    if _otel_log_level in _OTEL_LOG_LEVEL_TO_PYTHON:
+        _logger.setLevel(_OTEL_LOG_LEVEL_TO_PYTHON[_otel_log_level])
+    else:
+        _logger.warning(
+            "Invalid value for OTEL_LOG_LEVEL: %r. "
+            "Valid values: debug, info, warn, warning, error, critical. "
+            "Logger level unchanged.",
+            _otel_log_level_raw,
+        )
diff --git a/opentelemetry-sdk/src/opentelemetry/sdk/_logs/_internal/__init__.py b/opentelemetry-sdk/src/opentelemetry/sdk/_logs/_internal/__init__.py
index 956d9f28bd..639e0371d1 100644
--- a/opentelemetry-sdk/src/opentelemetry/sdk/_logs/_internal/__init__.py
+++ b/opentelemetry-sdk/src/opentelemetry/sdk/_logs/_internal/__init__.py
@@ -724,6 +724,7 @@ def emit(
         """
         if not self._is_enabled():
             return
+
         # If a record is provided, use it directly
         if record is not None:
             if not isinstance(record, ReadWriteLogRecord):
diff --git a/opentelemetry-sdk/tests/logs/test_logs.py b/opentelemetry-sdk/tests/logs/test_logs.py
index deb242f4a1..223591810a 100644
--- a/opentelemetry-sdk/tests/logs/test_logs.py
+++ b/opentelemetry-sdk/tests/logs/test_logs.py
@@ -14,13 +14,17 @@
 
 # pylint: disable=protected-access
 
+import importlib
+import logging
 import unittest
 from unittest.mock import Mock, patch
 
+import opentelemetry.sdk as _sdk
 from opentelemetry._logs import LogRecord, SeverityNumber
 from opentelemetry.attributes import BoundedAttributes
 from opentelemetry.context import get_current
 from opentelemetry.metrics import NoOpMeterProvider
+from opentelemetry.sdk import _OTEL_LOG_LEVEL_TO_PYTHON
 from opentelemetry.sdk._logs import (
     Logger,
     LoggerProvider,
@@ -35,7 +39,10 @@
     _LoggerConfig,
     _RuleBasedLoggerConfigurator,
 )
-from opentelemetry.sdk.environment_variables import OTEL_SDK_DISABLED
+from opentelemetry.sdk.environment_variables import (
+    OTEL_LOG_LEVEL,
+    OTEL_SDK_DISABLED,
+)
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.sdk.util.instrumentation import (
     InstrumentationScope,
@@ -463,3 +470,85 @@ def test_emit_readwrite_logrecord_uses_exception(self):
         self.assertEqual(
             attributes[exception_attributes.EXCEPTION_TYPE], "RuntimeError"
         )
+
+
+class TestOtelLogLevelEnvVar(unittest.TestCase):
+    """Tests for OTEL_LOG_LEVEL → SDK internal logger level."""
+
+    def setUp(self):
+        self._sdk_logger = logging.getLogger("opentelemetry.sdk")
+
+    def tearDown(self):
+        self._sdk_logger.setLevel(logging.NOTSET)
+        importlib.reload(_sdk)
+
+    def test_otel_log_level_to_python_mapping_accepted_keys(self):
+        expected_keys = {
+            "debug",
+            "info",
+            "warn",
+            "warning",
+            "error",
+            "critical",
+        }
+        self.assertEqual(set(_OTEL_LOG_LEVEL_TO_PYTHON.keys()), expected_keys)
+
+    @patch.dict("os.environ", {OTEL_LOG_LEVEL: ""})
+    def test_unset_env_var_does_not_modify_logger_level(self):
+        importlib.reload(_sdk)
+        self.assertEqual(self._sdk_logger.level, logging.NOTSET)
+
+    def test_invalid_value_warns_and_leaves_level_unchanged(self):
+        # "trace", "verbose", "none" are valid in other SDKs but not accepted here
+        for invalid in ("INVALID", "trace", "verbose", "none", "0"):
+            with self.subTest(invalid=invalid):
+                with patch.dict("os.environ", {OTEL_LOG_LEVEL: invalid}):
+                    with self.assertLogs(
+                        "opentelemetry.sdk",
+                        level=logging.WARNING,
+                    ):
+                        importlib.reload(_sdk)
+                self.assertEqual(self._sdk_logger.level, logging.NOTSET)
+
+    def test_case_insensitive(self):
+        for env_value, expected_level in (
+            ("DEBUG", logging.DEBUG),
+            ("WARN", logging.WARNING),
+            ("Warning", logging.WARNING),
+            ("cRiTiCaL", logging.CRITICAL),
+        ):
+            with self.subTest(env_value=env_value):
+                with patch.dict("os.environ", {OTEL_LOG_LEVEL: env_value}):
+                    importlib.reload(_sdk)
+                self.assertEqual(self._sdk_logger.level, expected_level)
+
+    @patch.dict("os.environ", {OTEL_LOG_LEVEL: "critical"})
+    def test_level_propagates_to_child_loggers(self):
+        importlib.reload(_sdk)
+        self.assertEqual(
+            self._sdk_logger.getChild("trace").getEffectiveLevel(),
+            logging.CRITICAL,
+        )
+        self.assertEqual(
+            self._sdk_logger.getChild("metrics").getEffectiveLevel(),
+            logging.CRITICAL,
+        )
+        self.assertEqual(
+            self._sdk_logger.getChild("logs").getEffectiveLevel(),
+            logging.CRITICAL,
+        )
+
+    def test_all_valid_values_map_to_correct_level(self):
+        cases = [
+            ("debug", logging.DEBUG),
+            ("info", logging.INFO),
+            ("warn", logging.WARNING),
+            ("warning", logging.WARNING),
+            ("error", logging.ERROR),
+            ("critical", logging.CRITICAL),
+        ]
+        for env_value, expected_level in cases:
+            with self.subTest(env_value=env_value):
+                with patch.dict("os.environ", {OTEL_LOG_LEVEL: env_value}):
+                    importlib.reload(_sdk)
+                self.assertEqual(self._sdk_logger.level, expected_level)