The male drove a minivan up to the window of a restaurant around 4 a.m. in the 5600 block of West Roosevelt Road, police said. He broke the service window and took the cash register drawer before fleeing the scene, police said.
It was not immediately clear how much money was stolen.
No injuries were reported and no one is in custody.
Area Four detectives are investigating.
The robbery comes after McDonald's CEO and President and CEO Chris Kempczinski said last month that Chicago crime is hurting recruitment and scaring employees.
Kempczinski said the city does not have an adequate plan in place to address the issues and prevent companies like his from joining the growing list of companies that have fled the Windy City. The CEO says Chicago is a "city in crisis."