The three-foot alligator is being held at the police station until it can be transferred elsewhere.
Police used a pole borrowed from a utility crew, a trash can and a small net to catch the alligator.
Buffalo Grove Police Sgt. Mike Millet says he initially suspected the resident had been drinking when the man called to report the reptile.
Officers spent about 90 minutes searching before cornering the alligator. Millet says his squad used a pole provided by a ComEd repair crew and the net to get the alligator into the trash can.
Officials say the reptile appears to be in good health and wasn't harmed during the capture.
It isn't clear how the alligator ended up in Buffalo Grove. This summer, two alligators were pulled from the Chicago River, and officials suspect they were pets that were released when they became too big to keep.
The Associated Press contributed to this report.