Ratten was axed by the Blues prior to their Round 23 clash with St Kilda, but finished the season at the club at which he spent a collective two decades - 255 games as a player and 116 as coach.
But the Blues' decision - and Ratten's choice to turn down an offer to take the vacant Port Adelaide job - was Hawthorn's gain, as they lapped up the 41-year-old's services as they attempt to go one better in 2013.
Ratten fills the void left by Cameron, who has sewed up his coaching future with a move to Greater Western Sydney where he will serve as an assistant to Kevin Sheedy in 2013, before assuming the senior job the following year.
But Hawks coach Alastair Clarkson was pleased with the calibre of Cameron's replacement.
"Brett is an excellent addition to our coaching line-up and will bring a great deal of experience and coaching nous to our club," Clarkson said on the Hawks' official website.
"He has impressive credentials as a coach and is a quality person, and I'm sure he will complement our team of coaches well."
Ratten said he was thrilled to be making the move to the Ricoh Centre, and will begin his stint there in November.
"It's an honour to join the club and I'm really excited to have the opportunity to work with Alastair and the other assistant coaches," Ratten said."I really respect how they play the game and I see this as a great opportunity for me and one I'm really looking forward to," he said.