The 62-year-old man was riding a bicycle when he was knocked down by the bus which was travelling along Boundary Street towards Kowloon City at about 5.37am.
The cyclist sustained head injuries and was rushed in an unconscious state to Kwong Wah Hospital, where he was later pronounced dead.
The 74-year-old bus driver was arrested for dangerous driving causing death.
The Special Investigation Team of Traffic, Kowloon West is currently investigating the case.