Ki enjoyed a promising debut season in the Premier League. Although he failed to replicate the scoring form he displayed at Celtic, his passing style drew praise from supporters and critics, and he finished the season with 38 appearances in all competitions. On 24 February 2013, Swansea City competed in the final of the League Cup. Ki played for over an hour in the final in an unfamiliar central defensive role. The tactical switch proved to be a success, as Swansea ran out comfortable 5–0 winners against Bradford City as Ki won his first trophy with the Welsh club.