 Bruce and Newcastle allowed Ki to ponder his options in search of more game time during the winter transfer window, and on 31 January 2020, he left the club by mutual consent.On 25 February 2020, Ki joined RCD Mallorca for the remaining of the season, with the Balearic club engaged in a relegation battle from the Spanish top tier.He made his La Liga debut on 7 March, replacing Takefusa Kubo in the last fifteen minutes of a vital 2–1 away win against Eibar, thus becoming the first Korean player to wear the shirt of Los Bermellones.