"My whole thing on marriage is personal," McCarthy, 36, told PEOPLE at Saturday's Los Angeles premiere of Nickelodeon's The Backyardigans Live: Tale of the Mighty Knights!
"I've done it. I've been there. My particular view on it is I don't need that piece of paper of commitment to prove my love," she says.
McCarthy brought son Evan, 6, to the event – a benefit for Malaria No More, a non-profit organization that provides mosquito nets to protect children in Africa.
Meanwhile, beau Jim Carrey was back home sipping coffee, she said.
Supports No on Prop 8Even though the couple have chosen to forgo a wedding, she isn't against the idea altogether – especially with the controversial Proposition 8 (seeking to overturn the legality of California's same-sex marriages) about to hit state ballots Nov. 4.
"I think people should have the right – anyone – to get married," says McCarthy, who later joined up with Tori Spelling and Dean McDermott (with son, Liam, 1, and McDermott's son, Jack, from a former marriage) at the event.
"I do believe in the right to have everyone else be able to do it. I couldn't imagine someone telling me not to do it because of my sexuality. I think everyone deserves to get married."