The actress and former Playboy playmate was named Monday to join the panel of the ABC weekday talk show.
Barbara Walters, who created "The View" in 1997 and has since served as a co-host, made the widely expected announcement on the air.
"We love her because she's fun, she's uninhibited and she's opinionated enough to help us begin the latest chapter in 'The View' history," Walters said.
McCarthy arrives at the start of the 17th season on Sept. 9.
She has previously made 17 appearances on "The View" and guest-hosted eight times.
The 40-year-old McCarthy began her career posing for Playboy and has since starred in TV sitcoms and appeared in films including "Scary Movie 3."
She has emerged as an activist campaigning about the dangers of vaccines, which she believes triggered her son's autism.
McCarthy will join "The View" as Joy Behar prepares to leave after being a fixture on the show since its premiere.
A remaining vacancy was created last week by Elisabeth Hasselbeck, who exited to join Fox News Channel. There is no word on when that slot will be filled.
And there will be yet another opening before much longer: Walters has said she is retiring from television next year.
Other co-hosts of "The View" remain Sherri Shepherd and Whoopi Goldberg.
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