Police officers were deployed to Handsworth Road in Handsworth at around 2pm to reports of a collision between a black Volkswagen Golf and a pedestrian.
The pedestrian, a man in his fifties, had left his car while he went into a nearby shop. A thief then jumped into the Golf and drove off in it.
As the owner tried to stop him, he was dragged along the road after being struck by the car and suffered serious injuries. He was later transported to hospital, where treatment is continuing today.
The car thief fled the scene in the Golf, by turning left into Fitzalan Road.
The Golf itself has not yet been found.
Eyewitnesses said at least seven police cars were deployed to the scene, and the road remained taped off for hours as officers carried out their enquiries.
Police said they are now appealing for witnesses to help them in their investigation.
South Yorkshire Police said: “Officers wish to speak to anyone who might have been in the area at the time and saw who heard anything suspicious, has CCTV which captured the incident or who was driving past and caught the incident on dash cam.”
Those with information should call 101 and quote incident number 383 of January 4.
Information can also be passed on to Crimestoppers, anonymously, by calling 0800 555111