Prosecutors in the northern city of Lille said investigating judges had determined that Strauss-Kahn, 64, who has been under investigation in the case since 2012, should be judged by a criminal court.
The decision came as a surprise after a public prosecutor had recommended in June that the inquiry be dropped without trial.
"We're not in the realm of the law, we're in ideology. We're sending someone to court for nothing," said Henri Leclerc, one of Strauss-Kahn's lawyers.
The so-called Carlton affair, named after a hotel in Lille, involves sex parties that Strauss-Kahn has acknowledged attending. He says he was unaware that the women who participated were prostitutes.
Strauss-Kahn is charged with "aggravated pimping." Pimping under French law is a broad crime that can encompass aiding or encouraging the act of prostitution. Strauss-Kahn was charged with the more serious form because it allegedly involved more than one prostitute.
The crime carries a maximum term of 10 years in prison and a fine of 1.5 million euros ($2 million).
The former French finance minister quit his post as head of the International Monetary Fund in 2011 after being accused of raping a maid in New York, a charge that was later dropped.