Mendy played his first competitive game for Leicester in a 2–1 defeat to Manchester United in the 2016 FA Community Shield on 7 August, coming on as a 63rd-minute substitute for Andy King. He suffered an ankle injury on his league debut at home against Arsenal on 20 August 2016 and was substituted in the 53rd minute. Mendy was sidelined for more than three months, and did not make his return until 7 December 2016 in a Champions League group stage match away to Porto, playing the entire game in a 5–0 defeat. He ultimately made only four league appearances for the season.