The death toll rose to 14 from the initially reported 13, after an injured passenger died upon arrival at the hospital, a spokesman of the hospital said.
The accident, which took place around 4 a.m. local time (2000 GMT Friday) when the bus was traveling from Johor Baru to Kuala Lumpur on the North-South Expressway in Johor state, was the worst bus crash since a Genting highlands accident in 2013 which left 37 people dead.
The identities of the victims were yet to be verified, but Bernama said the injured people included both Malaysian nationals and foreigners from Singapore and Myanmar.
It was not known yet what caused the bus to skid the road, but Johor Fire and Rescue Department Deputy Director Mohd Yusof Mohd Gunnos said initial investigation showed the road was in good condition.
Millions of Malaysians headed home or went traveling during the three-day Christmas holiday, most of them by car, making the main North-South Expressway crowded.