"Let that sink in. In the onslaught of news where we see the world backsliding into authoritarianism, this stands alone," Clooney said in an opinion piece, in which he called for a boycott of nine hotels owned by the Brunei Investment Agency.
Two of the hotels are in France, including Le Meurice in central Paris. Others are in the UK, Italy and the US, including the Beverly Hills Hotel and the Bel-Air hotel in Los Angeles.
"Every single time we stay at, or take meetings at or dine at any of these nine hotels we are putting money directly into the pockets of men who choose to stone and whip to death their own citizens for being gay or accused of adultery," said Clooney.
Homosexuality is already illegal in Brunei but under a new penal code based on Sharia law to be implemented on Wednesday, 3 April, it will now be a capital offence. The punishment for theft will be amputation of a hand or foot.
There have been previous calls for boycotts of Brunei after it first announced the measures in 2013. Implementation has been delayed as officials worked out the practical details, and dealt with heavy criticism.
Amnesty International urged Brunei to "immediately halt" implementing the new penalties, which it called “cruel and inhuman".
Phil Robertson of Human Rights Watch warned that implementation of the law "will quickly drive the country towards human rights pariah status in the eyes of foreign investors, tourists, and international agencies".