The actor will earn $3 million for his promotional work and will shoot a spot for the car campaign next week in Los Angeles, according to E! News.
Cadillac had no comment on the hiring, and Pitt's representatives have yet to confirm the news.
Pitt has long kept a Cadillac Escalade in his fleet of vehicles.
He has already been working on keeping in touch with his Asian audience and recently joined China's version of Twitter, Sina Weibo.
His first 'tweet' earlier this week read: "It is the truth. Yup, I'm coming..."
Last year, he made history and became the first ever Chanel No. 5 spokesman.
Watch a trailer for Brad Pitt's World War Z below: