ATK had been without a head coach going into the 2018-19 season after a failed experiment last season with Teddy Sheringham at the helm. Sheringham was sacked after a poor string of results but his replacement Ashley Westwood failed to get the club back on track as well.
Star signing Robbie Keane was announced as player-manager towards the end of the season as Westwood parted ways and ATK ended the season ninth on the table with 16 points from 18 games. Keane led his team to the round-of-16 of the Super Cup where they suffered defeat at the hands of FC Goa.
Goal had earlier reported that the Kolkata-based club were in negotiations with the Englishman.
After taking Kerala Blasters all the way to the finals of the 2016 edition, Coppell took charge of new entrants Jamshedpur FC in 2017-18 and took them to a fifth place on the table in their inaugural season.
The English coach is known for his defense-first approach and his teams are often built around a strong backline. Jamshedpur FC had the best defence in the league stage of ISL last season whereas ATK leaked 30 goals, the second-highest tally in the league.