Hughes, who had been working under West as Academy coach, had a distinguished playing career with Widnes and Great Britain. He later coached Widnes and Rochdale Hornets before taking over at St Helens in 1994.
Although he was sacked and replaced by Shaun McRae two years later, Hughes has been given much of the credit for assembling the side that succeeded Wigan as both cup and league winners last season.
Hughes, a specialist at developing young players at Saints, said: "There is even more talent at Wigan and I'm sure the club will be back among the honours before too long.
"Obviously, we were bitterly disappointed at going out of the Challenge Cup so early in the season, but we have got so much to look forward to with Super League and the World Club Championship. We have got a world- class side at Wigan and I am convinced that we will do well this season. I wouldn't have taken the job otherwise."
Hughes's first opportunity to put his stamp on Wigan will be in two friendlies against Castleford next month, followed by the opening Super League fixture at home to Halifax on 16 March.
The club's chairman, Jack Robinson, has paid tribute to West's 14 years at Wigan.
"Graeme has been a great servant of the club for a long time," he said. "He has played a huge part in our incredible run of success and we wanted him to stay as football manager, with Eric working alongside him and bringing with him a fresh approach.
"Unfortunately he turned the job down and has now decided to leave the club. To lose anybody who has put so much hard work into the club is a blow, but we now have to look ahead to a bright new future with Eric as coach."
West still sees the situation in subtly different terms. "I can't see it any way other than that I've been sacked," he said after taking his leave of Central Park yesterday.
The first new player Hughes will have at his disposal will be the Tongan centre Paul Koloi, who has been playing in New Zealand.Reuse content