The bus carrying 21 people -18 Chinese tourists and three Malaysians - was running downhill from Genting Highlands when the accident occurred at about 11 a.m., The Star newspaper reported.
Two Chinese men suffered head injuries and died on the spot, New Straits Times reported.
Others suffered minor injuries.
Initial investigation revealed the group of Chinese tourists were from Yunnan Province and they were visiting Genting Highlands, a popular entertainment and tourist destination, which has indoor and outdoor theme parks, casinos, as well as shopping centers.
According to the police, the 32-year-old bus driver did not have a license.
Malaysia has been competing with regional rivals to attract Chinese tourists. It recently agreed to extend its visa exemption for Chinese until the end of 2026.