The 19-year-old was on the No 5 First service in Glasgow city centre going to his home in Castlemilk when the incident happened in Glasgow city centre.
Police said he got on the bus on Sunday at 12.25am in Stockwell Street but tried to leave the vehicle as it approached Victoria Bridge.
He then made his way to the back of the bus as it was still moving.
He opened the emergency exit and jumped out, suffering serious head injuries. The teenager died at the scene.
A First Glasgow spokesman said: "Our thoughts are with the victim's family."