Sheen joined George Clooney, Brad Pitt and Kevin Bacon, among others, for the benefit launch of 8, a play about the Proposition 8 legislation which overturned laws to allow gay unions in the state.
The stars gathered at the Wilshire Ebell Theatre in Los Angeles at lunchtime on Saturday for rehearsals of the play, which recreated the courtroom drama surrounding the controversial legal battle, and then staged it for paying guests.
And passionate Sheen, who wowed as attorney Theodore Olsen onstage, was honoured to be part of the show.
He says, "Finally the public is allowed to hear and see what went on in that courtroom, so that's a revelation and I'm very proud to be a part of that."
Glee star Matthew Morrison and Matt Bomer, and Jamie Lee Curtis and Christine Lahti played the gay couples challenging the Prop 8 legislation, while Pitt played the judge presiding over the trial.
More than 200,000 fans logged on to YouTube.com to watch the show online, and it has now been revealed that over $2 millon (£1.25 million) was raised for the American Foundation for Equal Rights.