The singer debuted new ballad 'By the Grace of God' during her headline set at the iTunes Festival in London.
Perry explained that the song was the first one she wrote with Greg Wells back in November 2012, when starting work on her upcoming album Prism.
Wells joined Perry on stage to accompany her with the piano, as the star performed the new ballad for the first time.
The US star also performed her new promotional tracks 'Walking On Air' and 'Dark Horse', as well as her recent hit single 'Roar' at the Roundhouse show in Camden, London.
Perry's new album Prism will be released on October 21 in the UK and a day later in the US, and will feature 13 brand new tracks.
Watch the music video for Katy Perry's global hit 'Roar' below: