Adam Johnston, 6-year-old Barnaby's owner, told police someone broke into his apartment near Lake and Canal streets last week.
When he got home around 5 p.m. on May 18, he found his front door had been pried open and his dog gone.
Security video shows a man walking through the garage with a white dog under his arm. The video shows the man getting into a car that drove away.
PHOTOS: $5K reward offered to find stolen dog, owner says
Johnston said the $5,000 reward comes with no questions asked if Barnaby is returned.
"I don't care how it happened, what happened, who it is," he said. "I just want him back. I want to know he's safe. If you bring him back, no questions asked. I really don't care."
Johnston said anyone with information about the dog should call Chicago police.
The Sun-Times Media Wire contributed to this report.