The Real Housewives of New York City star invited pals Hoda Kotb, Tamar Braxton and Loni Love to commemorate the landmark on the show. The episode found Frankel and her friends eating the celebratory cake with their hands.
"Love that my girls aren't afraid to dig in!" Frankel captioned a picture of the moment she shared on Twitter.
She later thanked her pals on the social media site for coming out to support her on the big day.
"I LOVE my friends. Thank you so much for celebrating my 100th show with me!" she wrote on Twitter.
The celebration came a day after the reality star made headlines for sharing no-makeup selfie of her "Monday face."
Bethenny -- a show by executive producer Ellen DeGeneres -- made its debut in September 2013.