Belmullet is a coastal Gaeltacht town with a population of 1,019 on the Mullet Peninsula in the barony of Erris, County Mayo, Ireland. It is the commercial and cultural heart of the barony of Erris, which has a population of almost 10,000. According to the 2016 census 50% of people in the town were able to speak Irish while only 4% spoke it on a daily basis outside the education system.

The Mullet Peninsula —also known as the Mullet and sometimes as the Erris Peninsula—is a peninsula in the barony of Erris in County Mayo, Ireland. As of 2016 it has a population of 3963. It consists of a large promontory connected to the mainland at Belmullet, a town of about 1,000 inhabitants, by a narrow isthmus. There are several villages on the Mullet peninsula including Aughleam, Elly, Corclough and Binghamstown. The Peninsula is about 33 km (21 mi) long and ranges from 200 metres (660 ft) to 12 km (7.5 mi) wide. Its northernmost point is Erris Head. The peninsula's doglegged shape forms two bays, Blacksod Bay and Broadhaven Bay.