A passerby found the injured man in the driveway of a home on Yaldhurst Rd in the Russley area about 6.30am.
A cordon surrounded the property on the busy commuter route.
Two police cars were posted outside and a police forensic photographer was at the scene.
Detective Senior Sergeant Tony Hill said it was too early to confirm how the man received the injuries but police are treating the incident as a possible hit and run.
The man is described as being in his mid-40s, with short red hair, a goatee beard and tattoos.
"We are appealing urgently for anyone who may have seen this man, or any unusual activity, in the Yaldhurst Rd area near Riccarton Racecourse, overnight or this morning," said Mr Hill.
The injured man is in Christchurch Hospital.
Police do not believe he is associated with the address at which he was found.
Anyone with information should contact Christchurch police on (03) 363 7400 or Crimestoppers, anonymously on 0800 555 111.
