The show by self-styled "psychological illusionist" Derren Brown was broadcast on Sunday on Channel Four television, which said there would be a slight tape delay so transmission could be quickly ended if he blew his head off.
Brown carried out his stunt in an unnamed foreign country, since handguns are illegal in Britain.
A volunteer, picked by Brown from 12,000 hopefuls, put a bullet in one of the gun's six chambers. Brown then said he was reading the volunteer's mind to determine where the bullet was before putting the gun to his head.
Twice Brown put the revolver to his head and squeezed the trigger. On the third shot the illusionist pointed the gun away and fired. The chamber was empty.
After several minutes of silent contemplation Brown fired at his head and then quickly fired the live round into a wall of sandbags.
British police had earlier labelled the stunt "deplorable" and called for the show to be stopped, saying there were fears someone might copy it.
Britain has been shocked by a spate of gun attacks in the past week, including the fatal shooting of a jeweller in a family-run shop, the daylight machine-gunning of a man on a street and the shooting of three other men the following day.
Channel Four and Brown denied the Russian roulette stunt was irresponsible. The illusionist said it was designed to show the dangers of guns.