Eighty people were reported killed after gunmen burst into the Bataclan concert hall and took dozens hostage.
The siege ended when security forces stormed the building.
People were shot dead at bars and restaurants at five other sites in Paris. Eight attackers were later reported killed.
Police believed all of the gunmen were dead but it was unclear if any accomplices were still on the run after the string of near-simultaneous attacks.
Paris residents have been asked to stay indoors and about 1,500 military personnel are being deployed across the city.
The gunmen's motives were not immediately confirmed, but one witness at the Bataclan heard one of the attackers appear to express support for the militant Islamic State (IS) group.
"It's Hollande's fault, he shouldn't have intervened in Syria!" the man shouted, according to French news agency AFP, citing the French president's decision to take part in Western air strikes on IS.
Paris saw three days of attacks in early January, when Islamist gunmen murdered 18 people, attacking satirical magazine Charlie Hebdo, a Jewish supermarket and a policewoman on patrol.
What we know
-Le Carillon bar, 18 rue Alibert, 10th district - gun attack
-Le Petit Cambodge restaurant, 20 rue Alibert, 10th district - gun attack
-Stade de France, St Denis, just north of Paris - explosions near venue as France played Germany in football friendly
-La Belle Equipe, 92 rue de Charonne, 11th district - gun attack
-Bataclan concert venue, 50 boulevard Voltaire, 11th district - gun attack and hostages taken
-La Casa Nostra restaurant, rue de la Fontaine au roi, 11th district
The attack on the 1,500-seat Bataclan hall was by far the deadliest, where the gunmen opened fire on concert-goers watching US rock group Eagles of Death Metal. The event had been sold out.
The series of attacks not far from the Place de la Republique and the Place de la Bastille struck at the heart of the capital, before and after 22:00 (21:00 GMT) on Friday, when cafes, bars and restaurants were at their busiest.
Customers were singled out at a pizza restaurant, a Cambodian restaurant, a bar and a McDonalds outlet.
The only other target was the Stade de France, on the northern fringe of Paris, where President Hollande and 80,000 other spectators were watching a friendly international between France and Germany, with a TV audience of millions more.
The president was whisked to safety after the first of three explosions just outside the venue to convene an emergency cabinet meeting. Three attackers were killed there.
As the extent of the bloodshed became clear, Mr Hollande went on national TV to announce a state of emergency for the first time in France since 2005. The decree enables the authorities to close public places and impose curfews and restrictions on the movement of traffic and people.
Within an hour, security forces had stormed the concert hall and all four attackers there were dead. Three had blown themselves up and a fourth was shot dead by police.
Another attacker was killed in a street in eastern Paris, reports said.
Speaking after arriving at the concert hall, President Hollande said the attackers would be fought "without mercy".
US President Barack Obama spoke of "an outrageous attempt to terrorise innocent civilians".
UK PM David Cameron said he was shocked and pledged to do "whatever we can to help".