Grant Park closes at night but, some 500 demonstrators set up camp to sleep there following a march that involved about 2,000 people.
Police say they warned demonstrators they would be taken into custody. The arrests were mostly peaceful and came as protesters chanted "the whole world is watching."
They have since been released but are set to appear in court.
Protesters in at least three other U.S. cities were also arrested. In Phoenix, 46 people were arrested after refusing to leave a park, and in Denver, at least two dozen people were arrested for refusing to move out of the street.
The anti-Wall Street movement, in protest of Wall Street's role in the financial crisis and other grievances, has been growing. At least one protest overseas grew violent - in Rome, rioters hijacked what had been a peaceful gathering and smashed windows, tore up sidewalks and torched vehicles.
The Associated Press contributed to this report.
