Mehdi Nemmouche, a 29-year-old French citizen and radicalized Islamist, was arrested in Marseilles on May 30 by French authorities. In June, his lawyers said that he would fight extradition attempts.
Belgian Federal Police spokeswoman Tine Hollevoet confirmed the extradition took place Tuesday.
Prosecutors accused Nemmouche of carrying out the attack in Brussels that killed four people, including an Israeli couple in their 50s, after returning from a year in Syria. During his May arrest, police seized a Kalashnikov rifle that had been wrapped in an Islamic State of Iraq and Syria flag.