Firefox for Android comes with many pre-set search engines including Google as the default one. Unfortunately, it doesn’t include DuckDuckGo.com which is considered to be most privacy-friendly search engine on the web. Thankfully, Firefox for Android (and the desktop version as well) allows users to add more search engines to the browser and customize their search settings.
Here are the steps to add DuckDuckGo search engine to the Firefox on Android, which should be the same for other providers as well. First of all, visit DuckDuckGo.com in a browser tab and long tap in the search box. This would open a panel on the top, as shown in the following screenshot:
Now, tap on the magnifying glass icon on the right, which would prompt you to add search engine to the Firefox. Follow it to add the search engine to the browser. Thus, you have added DuckDuckGo to the Firefox. Next step would be making it the default search engine. For this, open the settings page from the main menu and select the “Search” option:
In Search settings, you can see all the search engines added to the Firefox. Tap on DuckDuckGo (or any other, if you want) to make it the default search engine. Hence, you can directly search on DuckDuckGo from the address bar (which is similar to Chrome’s omnibox) of the Firefox on Android.