As marquee manager, Coppell, 60, will work on building a nucleus of support staff incorporating the best of Indian and international talents. He will also play an important role in the selection of the team.
Coppell was the foremost right-winger of his generation known for his speed and work rate. He won domestic honours for Manchester United with 322 appearances and 53 goals.
He represented England in 42 games, including at the FIFA World Cup, from 1977 to 1983 when his career was cut short by an injury.
His mentoring of Crystal Palace and Reading resulted in both clubs achieving their greatest-ever successes in the English Premier League. He was twice named League Managers' Association 'Manager of the Year' when he was in charge of Reading FC.
"Indian Super League has laid a strong foundation in its last two seasons nurturing quality Indian football. Also, its unique format gives an opportunity to Indian players to play and compete against international talent, learnings that will strengthen the roots of football in India," Coppell said in a release after being named the coach.
"I have heard a lot about the strong fan support of Kerala Blasters FC, as also Kerala's strong legacy in Indian football. I believe in creating an environment for the players to win matches and am looking forward to working with the team and sharing my passion for the game with them!" the veteran coach said.