The former "Survivor: The Australian Outback" contestant and "The View" co-host revealed the news during the ABC daytime chat fest's "Hot Topics" segment.
"I'm nauseous," said Hasselbeck, "but I'm fine with that because it's all for a good cause."
At the beginning of the show, a big surprise was promised that would "change the ladies of `The View' forever." Co-hosts Star Jones, Joy Behar, Meredith Vieira (search) and Hasselbeck appeared on the stage with big fake bellies and snack food in hand in front of a cheering audience.
"They're all freaking out," Jones whispered to Hasselbeck.
Barbara Walters (search) asked the audience to guess which "View" co-host was pregnant.
"Barbara!" a person in the crowd screamed.
Hasselbeck told the co-hosts and audience she was 13 and a half weeks pregnant, due sometime around the end of March or beginning of April next year. She also said she and her husband, Tim Hasselbeck (search), an NFL quarterback for the Washington Redskins, didn't want to know the sex of the child.
In 2003, Hasselbeck filled "The View" seat left empty by Lisa Ling (search). Hasselbeck previously hosted "The Look for Less" on the Style network and designed shoes for Puma.