The diminutive player has signed a five-year contract with Arsenal with an option of a further year.
“I’ve been looking at Arsenal over the last couple of seasons and the trajectory they’ve been on,” Rice, who scored 15 goals in 245 games for West Ham, having joined the club as a 14-year-old following his release from Chelsea’s academy, said shortly after the official confirmation.
“Not last season but the season before, they [only] finished fifth, but you could see the style of play Mikel was implementing.
“Last season was an outstanding season, blowing pretty much every team out of the water with the exception of Manchester City,” the player added.
Speaking of the player, whose pursuit was almost scuppered by Manchester City, Arsenal manager Mikel Arteta, said, “He is a player with tremendous ability, who has been performing at a high level in the Premier League and for England for a number of seasons now.
“Declan is bringing undoubted quality to the club and he is an exceptional talent who has the potential to be very successful here.
“Declan has great experience in the Premier League at only 24 years old. He has captained a very good West Ham team and as we all saw, he recently lifted a European trophy.
“The responsibility and role he has taken on has been very impressive and we are really excited that he is joining us,” Arteta, who guided Arsenal to second place last season added.
His £105m fee makes him the most expensive England international. Jack Grealish held the record with his £100m move to Manchester City from Aston Villa two seasons ago.