Hollande, accompanied by Paris mayor Anne Hidalgo, Prime Minister Manuel Valls and the victims' families, unveiled a plaque at the Charlie Hebdo offices, where Saïd and Chérif Kouachi killed 11 people - cartoonists, other staff and a police officer charged with their protection - on 7 January 2015.
An unfortunate error - cartoonist Georges Wolinski's name was spelt with a y instead of an i at the end - meant that the plaque will be covered up again until the mistake has been corrected - within 48 hours, the city council has promised.
The president then went on to do the same at the spot nearby where another police officer, Ahmed Merabet, was shot dead and at the Hyper Cacher supermarket, on the east of Paris, where Amédy Coulibaly killed four people two days later.
A fourth plaque will be unveiled on Saturday in honour of a woman police officer killed by Coulibaly on 8 January last year.
The ceremonies to mark the Charlie Hebdo killings will end on Sunday with a rally in memory of the victims of January's and November's attacks and the planting of a "tree of memory" on Paris's central Place de la Concorde.
But the widow of the police officer charged with protecting one of the cartoonists, Charb, has accused the security forces of ignoring warnings that security was lax at the office and lodged a legal complaint for neglect.
Franck Brinsolaro was "sacrificed", his widow Ingrid said on Tuesday, claiming that he had complained that the office was about as secure as a sieve.
Interior Minister Bernard Cazeneuve responded that her feelings should be respected and her questions answered but defended the security service's overall record from opposition calls for an inquiry into the November attacks.
Since 2013 18 jihadi recruitment networks have been closed down and 11 "groups if individuals preparing attacks" have been arrested, he said, adding that six attacks have been prevented since last spring.
Some of the measures the government has taken since the November attacks have stirred up controversy, particularly among its own supporters.
A proposal to write the stripping of dual nationals convicted on terror charges of French nationality into the constitution has caused unprecedented divisions in the ruling Socialists' ranks and aroused opposition on the hard left and the way the state of emergency has been applied has been criticised.