diff --git a/sentry_sdk/client.py b/sentry_sdk/client.py
index 9f54088438..426734e385 100644
--- a/sentry_sdk/client.py
+++ b/sentry_sdk/client.py
@@ -56,6 +56,7 @@
     capture_internal_exceptions,
     current_stacktrace,
     datetime_from_isoformat,
+    deprecation_warning,
     env_to_bool,
     format_timestamp,
     get_before_send_log,
@@ -350,6 +351,13 @@ def _get_options(*args: "Optional[str]", **kwargs: "Any") -> "Dict[str, Any]":
     if rv["enable_tracing"] is True and rv["traces_sample_rate"] is None:
         rv["traces_sample_rate"] = 1.0
 
+    if rv["send_default_pii"] is not None:
+        deprecation_warning(
+            "The send_default_pii option is deprecated. Use data_collection "
+            "instead. "
+            "See https://docs.sentry.io/platforms/python/data-management/data-collected/"
+        )
+
     rv["data_collection"] = _resolve_data_collection(rv)
 
     # Do not add the event scrubber if data collection is enabled as it can remove data that's
diff --git a/sentry_sdk/utils.py b/sentry_sdk/utils.py
index a6420d84b2..4586ac5d5e 100644
--- a/sentry_sdk/utils.py
+++ b/sentry_sdk/utils.py
@@ -10,6 +10,7 @@
 import sys
 import threading
 import time
+import warnings
 from collections import namedtuple
 from contextlib import contextmanager
 from datetime import datetime, timezone
@@ -2253,3 +2254,12 @@ def _is_localhost(
 @contextmanager
 def nullcontext() -> "Iterator[None]":
     yield
+
+
+def deprecation_warning(msg: str) -> None:
+    """
+    Emit a warnings.warn about a deprecation.
+
+    For other types of warnings, use logger.warning().
+    """
+    warnings.warn(msg, stacklevel=3, category=DeprecationWarning)
diff --git a/tests/test_client.py b/tests/test_client.py
index 7d42fc4446..7dc3922285 100644
--- a/tests/test_client.py
+++ b/tests/test_client.py
@@ -1485,6 +1485,12 @@ def test_enable_tracing_deprecated(sentry_init, enable_tracing):
         sentry_init(enable_tracing=enable_tracing)
 
 
+@pytest.mark.parametrize("send_default_pii", [True, False])
+def test_send_default_pii_deprecated(sentry_init, send_default_pii):
+    with pytest.warns(DeprecationWarning):
+        sentry_init(send_default_pii=send_default_pii)
+
+
 def test_transaction_profiling_warns(sentry_init):
     with pytest.warns(DeprecationWarning, match="Transaction-based profiling"):
         sentry_init(profiles_sample_rate=1.0)