Reds legend Irwin has watched Kagawa in action for Borussia Dortmund and believes it won’t take long for the Japanese midfielder to become a crowd favourite at Old Trafford.
Irwin told ManUtd.com: "He’s the type of player that most United fans felt we needed, an attacking, all-action player.
"I saw him playing a couple of matches for Borussia Dortmund and he seemed a very talented player, lively with great technique. I know he was highly rated in Germany.
"I think he’ll be a great signing and fans should be excited by the prospect of him playing for us because he can run with the ball, create chances and score goals. He’s just what we need."
Kagawa quickly adapted to German football after moving to Borussia Dortmund from Japan and Irwin expects him to do the same in England.
"Physically it could be tougher than Germany but the Bundesliga can be quite tough, and other smaller players have shown that size doesn’t prevent you being a success in the Premier League," the ex-defender said.
"The manager will have done his homework on him – he went out to see him in the German Cup final when Dortmund beat Munich 5-2, in which he scored.
"So Sir Alex will have assessed him and decided he’s got what it takes to be a Manchester United player."
Kagawa, who will seal his move to Old Trafford if he passes a medical and obtains a work permit,