The actor will perform the stunt using a paintball gun with the help of illusionist Derren Brown.
Chris O'Dowd and wife Dawn Porter arriving for the premier of The Sapphires at the Odeon West End, London.
O'Dowd hopes to raise up to £10,000 for Channel 4's Stand Up to Cancer charity campaign through performing the stunt.
He will be offered five guns, with four being empty. However, one will be loaded and O'Dowd must correctly choose this gun to secure the money for charity.
The couple married in August this year and Porter has recently changed her Twitter name to Dawn O'Porter.
O'Dowd tweeted ahead of Friday's stunt: "This Friday I will #StandUpToCancer. I may get knocked down, but i will stand up again."
The couple are the latest stars to join the campaign which was set up by Gwyneth Paltrow and Cancer Research UK.
