The bus travelling from Johannesburg to Harare collided with the truck carrying cotton lint while overtaking another vehicle the corporation reported.
Eleven of the people died at the scene, while one died in hospital.
Some of the injured were ferried to Chibi Hospital and police were still verifying the names of the dead.
Masvingo province commanding officer, Senior Assistant Commissioner Fortune Zengeni, told the corporation that the Luqrey Coach bus had South African registration numbers.
Zengeni said preliminary investigations showed that the bus had been speeding when the collision occurred.
Road accidents were among the major killers in Zimbabwe, where highways are in constant disrepair, riddled with potholes due to years of neglect. – Sapa