After Elizabeth Hasselbeck departed the show last week, Walters said the show will take its time naming replacements, but she must have changed her mind.
"Jenny brings us intelligence as well as warmth and humor. She can be serious and outrageous. She has connected with our audience and offers a fresh point of view," Walters said in a statement. "Jenny will be a great addition to the show as we usher in an exciting new chapter for 'The View.'"
McCarthy, an actress and former Playboy playmate, has appeared on the show on 17 occasions, and guest-hosted eight times. She begins co-hosting at the start of the 17th season on Sept. 9.
"I'm beyond thrilled to be joining Barbara and the other amazing women at the table," McCarthy said in a statement. "I look forward to helping make hot topics a little bit hotter, and showing my mom that my interrupting skills have finally paid off."
The show also faces the loss of co-host Joy Behar this fall, and Walters is retiring from television next year.