The incident happened during a provincial equivalent of a “state of the nation” address.
Shortly before his collapse, Mr Mchunu called the province’s economic affairs minister to take over from him at the podium.
Government colleagues held him just as his knees gave in. The provincial health minister, Sbongiseni Dhlomo – who is also a medical doctor – climbed to the podium to assist the premier.
Paramedics rushed to the scene and he was taken to hospital.
Mr Dhlomo later confirmed on the government Twitter account that Mr Mchunu’s condition is not critical.
Mr Mchunu was treated in hospital and discharged.