Fifty fire paramedics and 19 firefighters took the oath at a ceremony.
The firefighters are part of the "Lewis Class", a group that applied and passed the 1995 exam but who didn't receive a job opportunity due to their test score.
After a lawsuit and a Supreme Court ruling, they were allowed to reapply.
Mayor Rahm Emanuel, Fire Commissioner Jose Santiago and ABC7 News Traffic Anchor Roz Varon took part in the ceremony.
