Dutch striker Makaay achieved 43 caps for the Netherlands, playing under current Reds boss Louis van Gaal, and ensures he is still in good shape for next month's big event.
"I've been doing a little bit of work and I play maybe once or twice a year," he said. "It's always nice to play at Old Trafford. It will be a decent match in Manchester because it's an amazing stadium. I think it's even better now than when I played there.
"I'm looking forward to the game. There is still time left so I need to get more training done and get fit. I'm sure it will be a great game for all the spectators who turn up to the stadium."
Fellow former Bayern player Hamann is also keen to take part, especially as all proceeds from the event go to Manchester United Foundation’s work in the local community.
"It's great to be able to give something back and help raise money for charity,” the ex-German international said. "I'm looking forward to it. I always liked playing against United because there were so many great games, and now we've got a match between two very successful teams with winning in their DNA. It might not be as competitive as a professional game but nobody likes to lose and it will be the same when we meet in June."
Makaay and Hamann will join the Bayern Munich All Stars as they take on Manchester United Legends on 14th June at Old Trafford. Legendary German player Paul Breitner will lead the Bayern team whilst Bryan Robson will captain a team of former Reds including Edwin van der Sar, Jaap Stam, Denis Irwin, Andrew Cole, Dwight Yorke, Paul Scholes and many more.
There is all to play for after a 3-3 draw at the Allianz Arena last August and the event promises to be a fun-filled family day out. There will be activities and a fun fair outside the stadium and a concert on the pitch pre-kick off with live music from top boyband Union J and 2014 X Factor winner Ben Haenow.
All money raised from the event will go to Manchester United Foundation. Tickets are on sale now from www.manutd.com/legendsareback or by calling 0161 868 8000.