diff --git a/rfcs/python_39.md b/rfcs/python_39.md
new file mode 100644
index 0000000..1cd8aa6
--- /dev/null
+++ b/rfcs/python_39.md
@@ -0,0 +1,43 @@
+# RFC 200: Bump minimum supported Python to 3.9
+
+## Summary
+
+Raise the minimum supported Python version from 3.8 to 3.9.
+
+## Details
+
+The project currently supports Python 3.8 and newer. Python 3.8 reached end
+of life in October 2024, and the broader Python ecosystem has largely dropped
+support for it. As a result, we have been unable to update several dependencies
+that now require Python 3.9 or newer.
+
+Historically, continued Python 3.8 support was required due to downstream CI
+integrations with Apple’s and Google’s infrastructure. These systems have since
+been updated and no longer depend on Python 3.8, removing the primary blocker
+for increasing our minimum supported version.
+
+Implementing this change will require several concrete steps:
+
+- Update CI jobs currently running on Python 3.8 to use Python 3.9.
+- Refresh vendored dependencies that were previously constrained by
+  Python 3.8 compatibility.
+- Re-run CI for Dependabot pull requests to allow dependency updates to proceed.
+  Some dependencies may now require Python 3.10 or newer; in those cases, we
+  should manually update to the latest release that remains compatible with
+  Python 3.9.
+
+## Risks
+
+Python 3.9 itself reached end of life in October 2025, which means we
+will encounter similar pressure to raise the minimum version again as
+dependencies may already require Python 3.10 or newer. Any further
+increase in the minimum supported Python version should be handled
+through a separate RFC, particularly to account for vendor requirements.
+
+There is also a possibility that some external users rely on Python 3.8
+support, especially those using Ubuntu 20.04 LTS with extended security
+maintenance through 2030. While this scenario is considered unlikely,
+because such users would need to depend heavily on wpt in an environment
+where Python upgrades are difficult and also not participate in the RFC
+process, we will work with affected users in such cases to identify a
+viable path forward.