Mozilla Firefox or Firefox for short is a web browser and not a search engine. Mozilla does not have a search engine service of their own. You can add a search engine in the Firefox web browser on Android. https://support.mozilla.org/en-US/kb/add-or-remove-search-engine-firefox https://support.mozilla.org/en-US/kb/change-your-default-search-settings-firefox edit: It looks like you may have been asking How to make Firefox the default web browser on Android?. https://support.mozilla.org/en-US/kb/make-firefox-default-browser-android