Newton was born in New Haven, Connecticut, the daughter of Thomas Newton and Jennifer Newton (née Chase), daughter of composer and arranger Bruce Chase and violinist Fannie (née Paschell) Chase. She is of English, Czech, Norwegian, French, and Scottish descent. Newton is a first cousin once removed of actress Sienna Miller.[3]
After graduation, Newton then moved to New York City and landed several roles in television commercials for such companies as the Olive Garden.[4] Newton also appeared in a PSA video about the dangers of drinking for Human Relations Media, called "Keg Party".
Newton starred in the television series Love Bites in 2011. The hour-long romantic comedy was created by executive producer Cindy Chupack, who worked on Sex and the City.[7]NBC announced the pick up of the series in May 2010.[8] However, with Newton announcing her pregnancy, co-star Jordana Spiro contractually obligated to stay with her other show, My Boys (which was later cancelled), and Chupack's desire to leave the show, Love Bites was pushed back to midseason.[9][10]Love Bites was ultimately aired in July 2011 on NBC and was cancelled after its first-season order of episodes was burned off.[11] In November 2011, Newton was cast on CBS's How I Met Your Mother as Quinn Garvey, a love interest for Neil Patrick Harris's character Barney Stinson where she played a stripper.[12] In 2013, Newton starred in the midseason Fox comedy series The Goodwin Games.[13] In 2018 Newton began appearing in a recurring role on the HBO TV series Divorce, playing Jackie Giannopolis, the new girlfriend of Thomas Haden Church's character.
On September 13, 2019, it was announced that Newton will once again team up with Urie on a sitcom project for CBS and Warner Bros. Television called Fun, for which both will co-star and co-executive produce with creator Michael Patrick King and fellow Ugly Betty showrunners Tracy Poust and Jon Kinnally.[14] However, the pilot is not moving forward.[15]
Newton met her husband, actor Chris Diamantopoulos, in a subway station in New York and they married on May 12, 2005.[4] It was announced on July 1, 2010, that Newton and Diamantopoulos were expecting their first child.[17] She gave birth to a son in early November 2010[18] and a daughter in early 2014.[19] Newton gave birth to her second daughter in 2020 and her third in 2022.[20]