Elizabeth Jean "Busy" Philipps was born in Oak Park, Illinois. Her parents gave her the nickname Busy because, as an infant, she was always moving, and the nickname stuck; it even appears on her driver's license. She attended Chaparral High School in Scottsdale, Arizona. She studied at Loyola Marymount University at the same time as former boyfriend, Colin Hanks and Linda Cardellini(her Freaks and Geeks and ER co-star).

She worked the toy-fair circuit as a real-life Barbie before making her show-business debut. She appeared on the UPN sitcom Love, Inc., in a role originally intended for Shannen Doherty The show lasted for one season (2005-2006) before being canceled. Since fall 2006, she had a major recurring role as Hope on ER.

She also played Joey's college roommate Audrey Liddell (46 episodes, 2001-2003) in Dawson's Creek, and "Karen" in the Wayons Bro movie "White Chicks".

She was ranked #58 on the Maxim Hot 100 Women of 2001.

She married Marc Silverstein in 2007 and in August 2008 she gave birth to a baby girl – Birdie Leigh Silverstein. She is an avid Tori Amosfan. Philipps is the godmother of actor Heath Ledger’s daughter – Matilda Rose Ledger.