A preliminary investigation into Thomas Fabius' financial affairs was opened in 2013, with police particularly interested in his purchase of a seven million euro Paris apartment believed to be linked to money laundering.
A source close to the investigation said that this apartment, located in an upmarket area in the French capital was raided on Tuesday morning.
His lawyer Cyril Bonan confirmed the 34-year-old's detention, but made no other comment.
Thomas Fabius also has had an arrest warrant issued against him by the Nevada state court in late October related to bad cheques totaling more than 3.2 million euros in several Las Vegas casinos in mid-2012.
Following this revelation, French far-right leader Marine Le Pen had called on Laurent Fabius to resign.