A Fire and Emergency New Zealand spokesman said it was notified at 6.30am about a truck that had gone into a ditch on State Highway 1, south of Milton.
Crews and appliances from Milton responded initially.
The driver was trapped underneath his vehicle, but was conscious and able to talk to rescue crews.
Extra-heavy-duty rescue equipment had to be brought from Dunedin and appliances from Dunedin Central and Lookout Point stations attended.
The driver was freed at 8.24am.
A St John spokeswoman said one ambulance and one rescue helicopter attended the crash.
The man was airlifted to Dunedin Hospital in a serious condition, she said.
The wife of the driver, who is from Mataura, told the Otago Daily Times her husband was in a stable condition in Dunedin Hospital as of yesterday afternoon.
She said he told her he was unsure what caused the crash as it happened "so quick".
On social media, she called for people not to judge him because the cause of the crash was not yet known.
The family was just pleased he was alive, she said.
