Gamers using macOS 11 Big Sur will need to upgrade their systems soon. Valve announced it will officially stop supporting Big Sur on October 15, 2025. After that date, the Steam client will no longer run on Big Sur or earlier macOS versions.
Why Valve Is Ending Support
Valve explained that the change is necessary because Steam uses a modified version of Google Chrome. Chrome no longer works reliably on outdated macOS versions. Future Steam features and security updates will require system components only available in macOS 12 Monterey or later.

Additionally, Apple stopped providing security updates for Big Sur back in 2023. This means devices running Big Sur are more exposed to malware and other threats. Valve is urging users to update their systems to stay protected and maintain full Steam access.
A Trend of Phasing Out Older macOS Versions
This move follows Valve’s 2023 decision to drop support for macOS 10.13 High Sierra and 10.14 Mojave. That earlier shift focused on compatibility issues with 32-bit games. The upcoming October update continues Valve’s push to modernize its platform and improve performance across newer Apple devices.
What Users Should Do
Mac users who still rely on Big Sur should upgrade to at least macOS Monterey to continue using Steam. Those with unsupported hardware may need to consider newer machines or explore alternative gaming options.
Looking Ahead
Valve has been making steady progress in supporting Apple’s latest tech. In June, it released a beta version of the Steam client with native Apple Silicon support. With this latest update, Valve reinforces its commitment to modern platforms while encouraging users to stay up to date.