The 20-year-old made 64 appearances for City and scored 21 goals, helping the Club to League Cup success in 2016.
He made his debut against Watford in August 2015 and two weeks later scored the winner away at Crystal Palace seconds after coming on as a late substitute.
His first senior hattrick capped a dazzling individual display in the 4-0 FA Cup win at Aston Villa in January 2016 and he ended his first campaign with an impressive 14 goals in all competitions, despite many of his appearances coming from the bench.
Last season saw him struggle for game time but his impressive goalscoring continued as he notched another seven, including the winner in the Manchester derby at Old Trafford in September.
He currently has the best goals-to-minutes ratio in Premier League history for any player scoring 10 or more goals.
Iheanacho has earned nine caps for Nigeria over the last two years, scoring six goals.
Everyone at Manchester City wishes Kelechi all the best with his new challenge.