She appeared on a few mid-1980s television series such as Growing Pains and the short-lived Fast Times, as well as made-for-television movies including The Thanksgiving Promise and Infidelity before landing a regular role in the 1988-1989 sitcom Day by Day with Douglas Sheehan, Linda Kelsey and Julia Louis-Dreyfus.

[3] During this time, in 1995, she starred in a made-for-television movie Beauty's Revenge which was also marketed in CD and DVD form as "Midwest Obsession".

"I started undereating, overexercising, pushing myself too hard and brutalizing my immune system," she told US Weekly.

[5] On February 18, 2010, she signed on to play Alan Harper (Jon Cryer)'s girlfriend, Lyndsey McElroy, in season seven of Two and a Half Men.

Starting in 2017, Thorne-Smith has starred in a series of television films, the Emma Fielding Mysteries based on the novels by Dana Cameron.

[11] During her career, she has graced the cover of numerous magazines such as Shape, Parade, Self, InStyle Weddings, Entertainment Weekly, TV Guide, Vogue Knitting and Fit Pregnancy.

On January 1, 2007, she married Roger Fishman, president of the marketing firm the Zizo Group and author of the book What I Know.