Mourners stopped in ones and twos by the building on the Rue Nicolas-Appert, where a plaque was unveiled on Tuesday.
Seventeen people died in January last year when gunmen targeted the magazine and a Jewish supermarket.
No official events are planned for Thursday, although President Francois Hollande is due to address the police.
Marine Le Pen, the leader of France's far-right opposition party Front National, is also expected to speak at some point during the day.
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As well as the memorial at the magazine's former office, a second plaque was installed where a police officer was shot, and a third at the Jewish supermarket.
On Saturday, a fourth plaque will be unveiled in the southern suburb of Montrouge, where one of the gunmen shot a policewoman.
The commemorations will culminate in a public event on Sunday in the Place de la Republique, where Parisians gathered in the wake of the attacks.
A 35ft (10m) oak "remembrance tree" will be planted in the square and veteran French musician Johnny Hallyday will perform Un Dimanche de Janvier (One January Sunday), a song recalling the vast march in Paris that followed the attacks.
Amid the commemorations, Charlie Hebdo has once again courted controversy with the cover of its special anniversary edition. It depicts God, bloodied and carrying a gun under the headline "One year on: The assassin still at large".
Parisians have laid flowers and lit candles at the former office of Charlie Hebdo ahead of the anniversary on Thursday of the attack on the magazine.