After one year of dating, she and Billy Joel married at his home in Oyster Bay, Long Island, on October 2, 2004. Lee's four years younger stepdaughter Alexa Ray Joel (Billy's then-18-year-old daughter from his marriage to Christie Brinkley) served as maid of honor. Lee's own father Steve Lee (born 1956) is six years younger than Joel.
She convinced Billy to leave the Hamptons and he bought a four story townhouse in West Village where they reside with two dogs.
Katie has worked in several restaurants and gourmet food and wine stores. In 2003, she helped to open Jeff and Eddy’s Restaurant where she served as the house fishmonger .
In 2006, she hosted the first season of Bravo's Top Chef. Critical reception to Joel's hosting style was less than enthusiastic, however, with many viewers citing her lack of culinary credibility and monotonic delivery as detrimental to the enjoyability of the show. As such, Bravo producers decided to replace her with a more lively Padma Lakshmi in an effort to boost ratings and bolster viewer reception.
Lee's first cookbook, "The Comfort Table" was published by Simon & Schuster .
Lee occasionally appears on Extra as a special correspondent. She is a contributing editor to Gotham magazine, and her culinary and lifestyle column, "Katie's Kitchen," is published weekly in its sister magazine Hamptons.
Lee sits on the council of Chefs for Humanity, a group that provides humanitarian aid worldwide and she is also a member of Les Dames d'Escoffier, an organization that educates and mentors women in the culinary profession.