The three-time Super Rugby title winner Carlos Spencer will play for the Blues at the Brisbane rugby tens tournament in February.
Spencer played 97 games for the Blues between 1996 and 2005, and was a key contributor in their Super Rugby championship wins in 1996, 1997 and 2003.
The 42-year-old joins the Blues as a wildcard selection following an online public poll in which he was a clear favourite with the club's fans.
Carlos Spencer with the Blues in 2003. Photo: Photosport
"It's going to be amazing to put that Blues jersey back on again," Spencer said.
"I am very excited to be running around with a bunch of young guys again."
Tournament rules allow each team to sign a wildcard, with this year's inaugural tournament featuring the likes of Wallabies stars Andrew Walker, Radike Samo and Morgan Turinui.
Spencer has remained extremely fit since retiring as a player in 2010.
"The body's pretty good," he said. "I'm actually training for the Cape Epic (an eight-day, 700km mountain bike race through South Africa's Western Cape) in March next year, so I'm doing a bit of cycling at the moment.
"I still have a lot of passion for the Blue jersey. To get back involved with that culture at a union that has given me so much over the years is going to very special.
"I've played a couple of social events over the last couple of years but these guys are a lot fitter, faster and stronger. I'll be relying on the young guys to put me into space and then back me up so I can offload it. I'm looking forward to the challenge."
Spencer will Julian Savea, Kurtley Beale, Conrad Smith, Karmichael Hunt, Liam Messam and Colin Slade at the tournament, which includes all Australian and New Zealand Super Rugby clubs plus invitational teams Samoa, Fiji, Pau and Japan's Panasonic Wild Knights.