Is It OK to Uninstall Microsoft Silverlight from Your Computer?
Why Silverlight is still on your machine
If "Microsoft Silverlight" shows up in your installed-programs list, it's almost certainly a leftover. At some point — maybe a decade ago — a website asked you to install it to watch video or use a web app, and it has sat there through every Windows upgrade since. The runtime doesn't announce itself, so most people rediscover it only while cleaning up their software list and wonder whether anything still depends on it.
What still uses it: almost certainly nothing
Two facts decide the question. First, Microsoft ended support for Silverlight on October 12, 2021 — no more updates or security fixes of any kind. Second, no browser you're actually using can load it: Chrome, Edge, Firefox, and Safari all removed the plugin architecture Silverlight required years ago (the full story is in why Silverlight won't run in modern browsers), and Internet Explorer 11 — the last mainstream browser that could host it — has been retired by Microsoft as well. An installed runtime that no installed browser can invoke is dead weight.
The narrow exceptions are organizational: a workplace that deliberately keeps a legacy line-of-business app alive through Edge's IE mode may still exercise the runtime — see does Edge's IE mode run Silverlight for how thin that path is. A rare desktop application may also have bundled Silverlight's out-of-browser mode. If your machine is company-managed, ask IT before removing anything; on a personal PC, those cases essentially don't apply.
Why unused end-of-life software is worth cleaning up
There's a general principle here that goes beyond Silverlight. Software that no longer receives security updates never gets another fix, no matter what is discovered about it later. That's why guidance on managing software risk — such as NIST's Guide to Enterprise Patch Management Planning (SP 800-40 Rev. 4) — treats unsupported software as something to be actively managed rather than left in place indefinitely: when a product can't be patched, the remaining options are isolating it or removing it. For a component you aren't using at all, removal is the simple end of that spectrum. The same logic, applied to the server side, is covered in the risks of keeping a Silverlight app deployed.
It's worth being calibrated rather than alarmist: a runtime that no browser will load has little opportunity to be exercised by a random website. The case for removal is less "urgent threat" and more "unmaintained code with no purpose" — the software equivalent of a dead bolt-on you'd rather not carry forward through the next decade of Windows upgrades.
How removal works
Silverlight uninstalls the same way as any other Windows program: through the standard Apps (or Programs and Features) list in Windows settings, with a restart of the browser afterward. On a Mac, the runtime lived as a plugin package rather than a normal application, which is one more reason the leftover tends to linger unnoticed. Nothing in modern Windows or any current browser depends on Silverlight, so removing it doesn't take anything else down with it.
If you later hit the one legacy site that still demands Silverlight, the honest answer is that reinstalling wouldn't have helped anyway — the browser-side support is gone regardless of what's on your disk. What end of support actually changed, and didn't change, is laid out in what Silverlight end of support means.