Pro players and Brit celebrities, including pop star Williams, represented England at the match, going head-to-head against the Rest of the World team, which was comprised of Harrelson, actors Mike Myers and Michael Sheen and celebrity chef Gordon Ramsay, among others.
Both squads were forced to take part in a penalty shoot-out to determine a winner after the game came to a tie.
Williams, who served as captain for the England team, failed to score a goal in the tense showdown, prompting Harrelson to participate in a subsequent sudden death heat.
And the Cheers star was celebrating after smashing the ball into the back of the net, clinching the win for the Rest of the World squad.
A relieved Harrelson later told reporters the game was “the most terrifying thing I have ever experienced”.
The event, held in Manchester, England, raised over $3 million (£2 million) for children’s charity UNICEF.