Michael Barrymore has admitted a charge of possession of cocaine during a hearing at Ealing Magistrates' Court.
The TV entertainer and another man were arrested last month after police reportedly found the Class A drug inside his Citroen DS3 vehicle.
Barrymore, 59, was fined £680 for the offence in addition to £100 in costs.
Officers had discovered a crash scene while on a routine patrol at the junction of The Vale and Dordrecht Road. It was not clear who had been driving at the time.
A small white rock was found by officers in Barrymore's trouser pocket, BBC News reports, and the star later tested positive for cocaine at a police station.
The My Kind of People host had also been charged with being drunk and disorderly following the incident.
Barrymore was recently accused of swearing at a waiter while drunk during the filming of Celebrity Coach Trip.
Last year, Barrymore claimed that he was "going back in" by dating a blonde woman 15 years after coming out. He later admitted that he was not dating the woman in question and had made the story up.
Barrymore appeared on Celebrity Big Brother as a contestant in 2006, finishing in second place, and was hired to co-host Big Brother's Little Brother two years later.