The marches mostly proceeded in a respectful silence, reflecting shock over the worst militant Islamist assault on a European city since 57 people were killed in an attack on London's transport system in 2005.
The attackers, two French-born brothers of Algerian origin, singled out the weekly for its publication of cartoons depicting and ridiculing the Prophet Mohammad. The bloodshed ended on Friday with a hostage-taking at a Jewish deli in which four hostages and the gunman were killed.
Some 2,200 police and soldiers patrolled Paris streets to protect marchers from would-be attackers, with police snipers on rooftops and plain-clothes detectives mingling with the crowd.
German Chancellor Angela Merkel, British Prime Minister David Cameron and Italian Prime Minister Matteo Renzi were among 44 foreign leaders marching with Hollande.
Merkel walked to Hollande's left and at his right was President Ibrahim Boubacar Keita of Mali, a country where France intervened to fight Islamist rebels two years ago to the day.
In a rare public display of emotion by the leaders of two powers, Hollande embraced Merkel, her eyes shut and forehead resting on his cheek, on the steps of the Elysee before they headed off to march.
Renzi said the fight against terrorism will be won by a Europe that is political, not just economic.
"The most important is the Europe of values, of culture, of ideals and that is the reason we are here," Renzi said.