"Daley Plaza will be open to public assembly and public activity" during the summits, the city's Public Building Commission wrote to the American Civil Liberties Union.
An organization of protesters -- the Coalition Against NATO/G8 War & Poverty Agenda -- called the reversal a victory, the Chicago Tribune reported Thursday.
"This is a small but important step," said Joe Iosbaker, the group's spokesman.
Iosbaker said that until this week city officials "would not make a commitment" to allow the group to protest in the plaza.
In November, MB Real Estate, which manages Daley Plaza for the city, denied the group's application to assemble there, saying, "We are not approving any permits for the use of the plaza" during the May summits.
Earlier this month, the commission told organizers to resubmit their application in January, when the application period for 2012 opens.
"MB Real Estate erred in even considering the application prior to Jan. 1," said Mimi Simon, a building commission spokeswoman. "Because the application was both too early and incomplete, at most, MBRE should have requested that the application be completed for consideration in January. … The previous response denying their application should not be a deterrent to them."