iPhone users who want fewer ads in Firefox no longer need a separate app. Mozilla has started a gradual rollout of a built-in Ad Blocker for Firefox on iOS, an experimental feature that “blocks many third-party ads and ad-related trackers before they load,” the company said in a blog post.
It’s off by default. Users who have it can turn it on under Settings > Browsing > Ad Blocker. Under the hood, Firefox uses Apple’s WebKit Content Blocker technology with the EasyList filter list, the same widely used list behind many ad-blocking extensions. Mozilla says it built the blocker into the browser because iOS doesn’t support extensions the way desktop and Android do.
What it doesn’t block
The exceptions matter as much as the feature. Ads served directly by the site you’re visiting will still show, and so will ads in search results. Sponsored shortcuts and other sponsored content on Firefox’s new tab page aren’t affected either.
AppleInsider pointed out the economics. Mozilla, like Apple with Safari, benefits from a search deal with Google, and in 2025 the nonprofit said 90% of its revenue came from Firefox, with roughly 85% of that from Google. Leaving search ads untouched keeps that relationship intact.
Mozilla framed the feature as a choice, not a crusade. “Advertising helps fund much of the open web, supporting the publishers, creators and websites people rely on,” the post says, while acknowledging that ads “can sometimes crowd the screen.” The blocker runs alongside Firefox’s existing Enhanced Tracking Protection.
What it means for advertisers
For marketers, the reach is limited. Firefox is a small player on iOS, the blocker is opt-in, and first-party and search placements get through. The bigger impact is on third-party exchange inventory, along with pop-ups and overlays, which AppleInsider says the blocker also targets. Publishers that rely on third-party programmatic ads could see slightly lower fill from Firefox iOS users who switch it on. Direct-sold and first-party ads are unaffected.
Mozilla is asking users to report missed ads and broken sites on Mozilla Connect while the feature is still experimental.
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