The Co-op, also an official partner of The RFL, has also re-signed up ex-St Helens player Paul Sculthorpe for a second year, to form the brand ambassador line up.
The deal was brokered by Co-op's sponsorship agency Generate Sponsorship.
Rooney, a full-time player for Barrow Raiders, has previously played for Wakefield Trinity Wildcats in the Super League and also Featherstone Rovers. Rooney still holds the record for the most points scored in a single season during his time at Featherstone Rovers.
Sculthorpe played over 250 times for St Helens and won four Super League Grand Finals, four Challenge Cups and two World Club Challenges before his retirement in 2008 and has signed for a second year as a 'Good for Everyone' ambassador for The Co-op.
Liz Matkin, head of sponsorship at the Co-operative Group's, said: "It is important for us to have ambassadors who fans of the teams in The Co-operative can relate to and both Paul and Jamie understand the importance of the Championships to the game.
"Both men also respect and strongly support what The Co-operative is trying to achieve for fans, clubs and the sport of Rugby League as a whole."
Matkin said: "They're high profile, inspirational and respected figureheads for us and that means, in addition to adding value to our activity with clubs and their supporters we'll also be able to reach beyond our traditional heartland areas."
The Co-op has been title sponsors of the Co-operative Championships since 2007 and official partner of the RFL since 2008.