Jóhann Gísli has been playing keyboard instruments from the age of 8, when he began his piano studies at the Kópavogur School of Music. He started playing the harpsichord when he was 11 years old, at first alongside the piano, but exclusively for the past four years. Jóhann Gísli completed an advanced level examination in harpsichord performance last spring and has continued his studies under the guidance of Guðrún Óskarsdóttir, who has been his harpsichord tutor form the very beginning. As well as playing the harpsichord, Jóhann Gísli studies history at the University of Iceland.

Jóhann Gísli has played in various chamber music groups, as well as performing with the Reykjavik Youth Orchestra and the Iceland Youth Symphony Orchestra.