Mayor Rahm Emanuel flipped the tree switch at 5 p.m. during the 98th annual tree lighting ceremony in Daley Plaza.
ABC7 Chicago's Mike Caplan and Windy City LIVE's Val Warner helped light the tree.
The 55-foot Colorado Spruce comes from the Spangler family in Western Springs. They also helped with the lighting.
The tree features 5,800 multicolored lights and a five-pointed star perched on the top.
Also Wednesday, Christkindlmarket returned to Daley Plaza. It opens daily at 11 a.m. The traditional German Christmas market will be open through Christmas Eve.