London's Metropolitan Police said the 30-year-old cyclist was pronounced dead about 30 minutes after the 7:45 p.m. accident about 1.5 kilometres north of the Olympic Stadium.
The accident occurred near the park's northern boundary, near facilities for Paralympic athletes and the Olympic Velodrome. Bus transportation in and out of the park was halted for more than two hours.
Ambulances including a helicopter-borne unit tried to save the man.
The Metropolitan Police said no one aboard the bus was reported injured and nobody was arrested. Detectives have launched an investigation.
"The police are investigating the accident and our thoughts are with the cyclist's family," the London Olympic organizing committee said in a statement.
Journalists covering Olympic events Wednesday night were told that media shuttle buses were suspended for the evening and were given other ways of getting to venues and hotels.