Tara Luhve said her son's dog Loki was inside her Honda Pilot when the vehicle was stolen on Saturday in the 1100 block of North Vermont Avenue.
She said she left the vehicle running to keep Loki cool while she stepped away.
Police ended up finding the family's SUV soon after, but Loki was nowhere to be found.
The Pomeranian mix was found under a freeway near Temple Street and Virgil Avenue and was returned to Luhve's family on Tuesday - just in time for her son's birthday celebration.
Video shows the sweet reunion and an excited Loki getting showered with love.
"I'm going to pick up my son right now from his school, he was supposed to be taking tests, it's his birthday today ... I'm going to come back to him with his dog!" said Luhve.