The crash was one of a dozen in the city reported to emergency services yesterday morning, prompting police to urge motorists to limit non-essential travel.
Snow fell in Dunedin's hill suburbs and ice made travel treacherous on many streets.
Emergency services were called to Maclaggan St shortly before 4am after a passerby found a 24-year-old man trapped inside his red BMW after it skidded 70m and hit a pole.
The Fire Service freed the unconscious man, who was taken to Dunedin Hospital.
Acting Senior Sergeant Tania Baron said the casino worker was driving down Serpentine Ave when the car hit black ice and skidded before hitting the concrete pole.
Acting Snr Sgt Baron said the serious crash unit was investigating, and while alcohol was not a factor in the crash, inquiries into whether he was wearing a seat belt continued.
The majority of crashes yesterday morning, including a three-car pile up in Stuart St, were the result of motorists losing control on ice.
Other traffic incidents were reported in York Pl, London St and in Abbotsford.
