Around 700,000 people took part in similar marches in cities outside Paris on Saturday and 4,000 demonstrated in the French Pacific territory of New Caledonia on Sunday evening local time.
French political leaders from across the political spectrum, including Socialist President François Hollande and his right-wing predecessor Nicolas Sarkozy, were due to attend.
So were 40 world leaders, including the UK’s David Cameron, Germany’s Angela Merkel, Israel’s Benjamin Netanyahu, the Palestinians’ Mahmoud Abbas, Turkey’s Ahmet Davutoglu, Mali’s Ibrahim Boubacar Keita and Gabon’s Ali Bongo.
The rally will mark the first time since 1990 that a French president has taken part in a demonstration.
“This is an unprecedented march, it will go down in history,” Prime Minister Manuel Valls said on Saturday. “It must be strong, dignified and show the power and dignity of French people who will shout their love of freedom and tolerance.”
But far-right leader Marine Le Pen called on her members to join marches in provincial towns but not in Paris, because her Front National (FN) has not been formally invited to take part, claiming that the “republic has been taken hostage”.
Her father, the party’s founder Jean-Marie Le Pen, on Saturday declared “Je ne suis pas Charlie” in reference to the solidarity slogan taken up around the world.
While he was “touched by the deaths of 12 French compatriots”, he could not defend the “anarcho-Trotskyist spirit” of a paper that “called for [the FN’s] dissolution in a petition not long ago”.
There were critics on the left, too.
Left Party leader Jean-Luc Mélenchon criticised Valls’s “takeover” of the demonstration, insisting that campaign groups and unions should have been charged with organising it.
The far-left New Anticapitalist Party (NPA) refused to go, one of its leading members, Alain Krivine, telling RFI that it was a “masquerade”, especially because of the presence of world leaders, some of them from countries where press freedom and women’s rights are tightly restricted.
The consensual mood also troubled some of Charlie Hebdo’s surviving cartoonists.
“We vomit on all these people who suddenly say they’re our friends,” said Dutch cartoonist Bernard Holtrop, pen name Luz. “We have lots of new friends, like the Pope, Queen Elizabeth or [Russian President Vladimir] Putin. It makes me laugh.”
Thousands of people who had never seen the paper demonstrated against it when it published cartoons of the prophet Mohammed a few years ago, he pointed out, adding “Now it’s the same - if people are demonstrating for freedom of expression, that’s a good thing, of course.”
Last November Charlie Hebdo issued an appeal for financial help because its circulation had fallen to 30,000 a week.
“They’re making us bear a symbolic burden that does not exist in our drawings and has gone a bit beyond us,” another cartoonist, Luz, told the Inrocks magazine.
“In the end, this symbolic burden is everything Charlie Hebdo always worked to destroy symbols, knock down taboos and crush fantasies.”
The huge security operation included snipers, plainclothes and anti-terror officers.
The march was to follow two routes to reduce congestion with parking restrictions and several metro stations will be closed.
Around 1,350 troops will be patrolling the greater paris area.
Public transport in the Paris region was free on Sunday to enable people to attend.
France remained on high alert Sunday.
A leader of Al-Qaeda in the Arabian Peninsula, on whose behalf the Kouachi brothers claimed to have attacked Charlie Hebdo's offices last Wednesday, has threatened fresh attacks on France .
And police were still searching for Hayat Boumeddiene, the girlfriend of Paris gunman Amedy Coulibaly, although Turkish officials said Saturday that she might have fled to Syria.