Salah Abdeslam, 26, is a childhood friend of the suspected ringleader of the attacks and is suspected of driving a car carrying a group of gunmen who took part in the shootings.
He and four other suspects were detained in a raid in Molenbeek, including three members of a family who allegedly sheltered him. Abdeslam was shot in the leg, officials said.
Helmeted police with riot shields cordoned off the area, and two explosions were heard.
France’s BFM television broadcast images of police tugging a man with a white hooded sweatshirt toward a police car, as he dragged his left leg as if it were injured.
The Islamic extremist attackers killed 130 people at a rock concert, the national stadium and cafes on November 13 in Paris, in the country’s deadliest attacks in decades.
Belgian prime minister Charles Michel called the arrests a success in the “fight against terrorism”.
He said he spoke to President Barack Obama about the arrest, and the White House said US officials have been in close touch with French and Belgian officials about the investigation into the Paris attacks.
French president Francois Hollande congratulated the Belgian government for an operation that lasted several weeks. He warned that the investigation is not over and said authorities would continue to pursue anyone involved in financing or organising the attacks.
Two other people believed to be linked to the attacks were still being sought, including fellow Molenbeek resident Mohamed Abrini and a man known under the alias of Soufiane Kayal.
The capture of Abdeslam came after Belgian authorities said they found his fingerprints in an apartment raided earlier this week in another Brussels neighbourhood.
In that raid, a man believed to have been an accomplice of Abdeslam — Mohamed Belkaid — was shot dead, Belgian prosecutors said. But two men escaped from the apartment, one of whom appears to have been Abdeslam.
Federal prosecutor Eric Van der Sypt said it was possible Abdeslam had spent “days, weeks or months” in the apartment.
Most of the Paris attackers died on the night of the attacks, including Abdeslam’s brother Brahim, who blew himself up. Brahim Abdeslam was buried in the area on Thursday.
Abdeslam slipped through a police dragnet to return to Brussels after the bloodbath in Paris, and though the target of an international manhunt, had not been found.
At one point during yesterday’s police operation, a phalanx of officers in camouflage, masks and riot helmets marched through the neighbourhood with guns and automatic weapons drawn, escorting people out of buildings.
Abdeslam’s exact role in the attacks is not clear. The car he drove was abandoned in northern Paris, and his mobile phone and an explosive vest he had apparently used were later found in the Paris suburb of Montrouge, raising the possibility that he aborted his mission, either ditching a malfunctioning vest — or fleeing in fear.
The Islamic State group claimed responsibility for the attacks, in which Belgian nationals played key roles.
On Tuesday, a joint team of Belgian and French police showed up to search a residence in the Forest area of Brussels in connection with the Paris investigation. They were unexpectedly fired upon by at least two people inside. Four officers were slightly wounded.
An occupant of the residence was shot dead by a police sniper as he prepared to open fire on police from a window. Police identified him as Belkaid, 35, an Algerian national living illegally in Belgium.
A Kalashnikov assault rifle was found by his body, as well as a book on Salafism, an ultraconservative strain of Islam.
Belgian authorities initially said Belkaid had no known background in radical Islamic activities. But yesterday afternoon, prosecutors issued a statement saying he was “most probably” an accomplice of Abdeslam.