An ad blocker is supposed to block ads. The one Mozilla began rolling out to Firefox for iOS in mid-August blocks a fair number of them, then stops at two kinds on purpose.
Mozilla documented the feature in a support article that appeared earlier this month, and The Register reported the rollout on 17 August 2026. It is switched off by default, labelled experimental, and reaching users in stages, so the setting may not exist on your phone yet even after you update.
When it is on, Firefox uses a filter list based on EasyList to block ads before they load. That covers third-party advertising networks and exchanges, ad-related trackers, many of the third-party ads that websites serve, and intrusive formats such as pop-ups and overlays.
Firefox will not block ads on search engine results pages, including Google, Bing and DuckDuckGo. It also leaves sponsored content on the Firefox Home and New Tab pages alone. Those two surfaces are where Mozilla earns money, from its search deals and from its own sponsored tiles, and Mozilla gives no reason for either exclusion in the support article. The Register raised the search revenue question and pointedly declined to draw the connection itself. Mozilla does link its own Respectful Ads page from the bottom of the same article, which is as close to an explanation as anything on the record.
Mozilla adds its own caveat, which is worth repeating because it sets expectations: sites serve ads in ways the current filter list does not cover, so some will still get through.
Mozilla names no app version. PiunikaWeb, testing on a device, reported that the toggle turned up in the stable build numbered 154, that an ad which the beta build caught was still loading in stable, and that video ads went through in both builds. That is one outlet’s hands-on result rather than a confirmed defect, but it matches Mozilla’s own experimental labelling.
Once the rollout reaches you, the switch sits in the app. Open the menu, go to Settings, scroll to Browsing, and turn on Ad Blocker under Content. You can also reach the same switch from the Site menu while a page is open, which is the faster route when a page breaks and you want to let it load normally.
What this means if you browse on an iPhone
Treat this as a convenience feature, not a replacement. If you installed a content blocker to get rid of ads on search results or in video players, keep it: those are exactly the two areas Firefox has ruled out or has not solved yet. What you gain is one switch inside the browser you already use, with nothing extra to install and nothing to configure.
If the setting is not there, you are waiting on the rollout rather than doing something wrong. Update the app, check again in a few days, and grab the current build from our Firefox download page if you are starting fresh. Anyone who wants blocking that is on by default already has Brave’s download page as the other route on iOS.
Source: Block ads in Firefox for iOS
