The French outfit have confirmed they have secured the services of the 27-year-old winger as the two clubs prepare to face each other in the European Champions Cup this weekend.
Ireland international Zebo has admitted it was a tough decision to call time on his successful spell with Munster, but feels he is joining a club with similar ambitions in Racing for next season.
He told the club's official website: "I like to feel surrounded, like family, and I know that in Racing it will be the case. It is also a club that has a long history, a tradition, like Munster, but at the same time a very ambitious, forward-looking club focused on winning.
"It is the very high level, like Munster, without denying the human side. In this sense the two clubs have a lot in common. I am a very determined person, a real competitor, but I also need human warmth in everyday life."