Redknapp, who led the Cherries to their highest ever finish in 1989, will not have an official title but will offer his advice and expertise to all aspects of the club.
The former Portsmouth, West Ham and Tottenham boss will also travel with the Cherries squad to Huish Park tomorrow as they take on second placed Yeovil.
Chairman Eddie Mitchell was delighted with the news and believes the 65-year-old will prove to be an invaluable asset for the club.
“I met Harry for a chat this morning and he offered to come in on a voluntary basis,” Mitchell told afcb.co.uk.
“He still has a passion for the club and for football, and he’s got too much to offer for us to let him slip through our fingers.
“It’s been in my mind for quite some time to get him involved, and the timing seems to be perfect for us to tap into his knowledge.”
Both Groves and Brooks were part of Redknapp’s backroom team during his second spell in charge at Fratton Park, which included winning the FA Cup in 2008, and Mitchell hopes they can enjoy success at the Goldsands Stadium.
“Paul and Shaun will still have the final say on all football matters, there’s no doubt about that. They’re very astute people and they’re not above listening to anyone, and I’m sure they can learn from him,” he said.
“They have both worked with him before and I think there’s only person who would be able to get on that coach tomorrow without Paul and Shaun rejecting the idea, and that one person is Harry.”