Nicole Richie sunglasses tank top gym sweat jean jacket

Nicole Richie looked ultra-thin (and a little sweaty!) as she exited a gym near her LA-area home, on Tuesday.

The House of Harlow and Winter Kate designer is gearing up to join Jessica Simpson, Elle Macpherson, and designer John Varvatos on NBC's upcoming contestant show, Fashion Star.

The fashionista will serve as a celebrity mentor to contestants who are competing for a major retail contract with a high-end department store.

We haven't seen the busy mamma of two on the small screen since she starred alongside former BFF Paris Hilton on The Simple Life, in 2003.

Welcome back, Nicole!