How To Enable uBlock Origin | Install On Firefox & Chrome

Enable uBlock Origin most reliably through Firefox installation from Mozilla Add-ons, or use a version-sensitive Chrome workaround with developer flags.

Deciding how to enable uBlock Origin starts with which browser you use. Firefox offers a clean, officially supported install from Mozilla’s add-ons page. Chrome requires a multi-step workaround that changes with each browser update and grows less reliable over time. The extension itself is the same free, open-source content blocker either way — a filter-based tool that blocks ads, trackers, and malicious scripts before they load. What differs is the setup complexity and long-term stability.

Installing uBlock Origin On Firefox: Official Add-Ons Method

Firefox remains the most reliable browser for uBlock Origin because it still supports Manifest V2 extensions directly. The extension is listed in the Mozilla Add-ons directory and installs like any normal add-on, with no flags, developer modes, or workarounds required.

1. Open the Mozilla Add-ons page for uBlock Origin’s Firefox install page.
2. Click Add to Firefox.
3. Approve the permission prompt — the extension needs to read and modify data on websites in order to inspect requests, hide ad elements, and stop trackers before they load.
4. Verify the uBlock Origin icon appears in the browser toolbar. If you don’t see it, right-click the toolbar, select Customize toolbar, and drag the icon into place.
5. Open about:addons in the address bar and confirm the extension shows as Enabled.
6. Open the uBlock Origin dashboard by clicking the icon and selecting the gear icon. Go to Filter lists, then click Update now to pull the latest blocking rules.
7. Check that the current site isn’t whitelisted. On the uBlock Origin popup, the power button should be blue — gray means blocking is off for that site.

Once enabled, uBlock Origin starts blocking ads and trackers immediately. Firefox users rarely encounter the compatibility issues that Chrome users face, because Mozilla hasn’t deprecated the extension framework that uBlock Origin relies on.

Enabling uBlock Origin In Chrome (Version-Sensitive Workaround)

Chrome’s gradual rollback of Manifest V2 support means uBlock Origin no longer installs from the Chrome Web Store on recent versions. A workaround exists using developer flags, but the exact flag name changes with each Chrome milestone — what worked on Chrome 139 may not work on Chrome 143. This method is not permanent and may break when Google updates its MV2 policy.

The current workaround sequence, verified across multiple 2026 guides, follows this order:

1. Type chrome://flags in the address bar and press Enter.
2. Search for temporary unexpire flags for your current Chrome milestone — for example, temporarily unexpire M143 flags and M144 flags on recent 2026 builds. Enable whichever ones appear for your version.
3. Search for Allow legacy extension manifest versions and enable it.
4. Rel launch Chrome for the flags to take effect.
5. Download the uBlock Origin Chromium package from the official GitHub repository.
6. Extract the downloaded archive. The working folder is uBlock0.chromium, not the top-level archive folder — loading the wrong path is one of the most common errors.
7. Go to chrome://extensions, toggle on Developer mode in the top-right corner, then click Load unpacked and select the uBlock0.chromium folder.
8. If uBlock Origin stops working after restarting Chrome, add this command-line flag to the Chrome shortcut target, with a space before it: --disable-features=ExtensionManifestV2Unsupported,ExtensionManifestV2Disabled

This workaround keeps uBlock Origin running on Chrome today, but each new Chrome version risks breaking it. The flags, the manifest support, and even the load-unpacked method itself could all change without warning.

Which Browser Works Best For uBlock Origin?

The table below compares the Firefox and Chrome paths across the factors that matter most for long-term use.

Common Mistakes That Look Like It’s Not Working

Most “uBlock Origin isn’t working” reports come from a few predictable errors. The table below covers both browsers.

If you’ve checked all these and uBlock Origin still isn’t blocking, try a fresh install. On Firefox, remove the extension from about:addons and re-add it. On Chrome, disable and re-enable the unpacked extension, then update the filter lists.

Enabling uBlock Origin Now: Your Next Step

For a setup that works today and stays working through future browser updates, install uBlock Origin on Firefox from the Mozilla Add-ons page. The whole process takes under two minutes with no flags, no developer modes, and no command-line tricks. Chrome users can keep the extension running through the workaround above, but should expect to reapply it each time a new Chrome milestone lands — and should plan for the day Google closes the MV2 loophole entirely. Either way, the extension itself is identical, and once it’s running, the blocking performance is the same on both browsers.