The 34-year old, who was capped three times by the France national team, has joined the Revs as a free agent after his contract with Lazio expired last June.
Revs coach Steve Nicol said it was vital he brought in a player of Dabo's experience.
"It was really important," Nicol said. "He finished playing with Lazio (after last season). He'd had a couple of months where he didn't play. As far as his ability is concerned, there was never a doubt."
It is likely that Dabo will used as a holding midfielder - an area which Nicol admits his side lacked plenty last season.
"I think one of the things we didn't do well last year was possess the ball," Nicol said. "If there's one thing he can do, it's possess the ball. Straight off the bat, that's what we're looking for from him."
Dabo joins fellow Frenchman and new signing Didier Domi at Gillette Stadium as the first of four key signings with a central defender and a wide midfielder still expected to sign with the Revs in the near future.