The first mosque in London, inaugurated on October 23, 1926, with the cost of £6,223, the construction of the mosque and land was financed entirely by the donations of Ahmadi Muslim women in Qadian. The designer of the mosque was Thomas Mawson. The foundation stone was laid in 1924 by Hazrat Mirza Bashiruddin Mahmud Ahmad (ra). It was later inaugurated by Khan Bahadur Sheikh Abdul Qadir.

It was visited by the crown prince of Saudi Arabia, the founder of Pakistan, Muhammad Ali Jinnah and the Crown Prince of Saudi Arabia, Faisal Bin Abdul-Aziz visited the mosque in 1935 as did his predecessor, King Saud.

The Fazl Mosque sustained no damage from WW2 and the Ahmadiyya Muslim community took part in various relief efforts for victims of the war and its neighbours affected by Nazi air raids, bombings and the “London Blitz”. The mosque was also used as a refuge during the war.

The mosque and its surrounding buildings have been the international headquarters of the Ahmadiyya Community from 1984 to 2019.