Julie Halston was born Julie Abatelli in Suffolk County, New York, and was raised in Commack, Long Island. She is the daughter of Julia Madeline "Dolly" (née Gardner), a teacher's assistant, and Rudolph "Rudy" Abatelli, who worked in tobacco sales. Her father is Italian American and her mother of Irish and German descent. Halston graduated from Hofstra University in 1976 with a BA in theater arts.

Halston's television credits include roles in "Sex and the City" (Bitsy von Muffling), "Law & Order", "My So-Called Life", and "Law & Order: Criminal Intent". She played Tina Carmello on the CBS sitcom "The Class" between September 2006 and March 2007. She appeared in "A Very Serious Person", "The Juror", "Addams Family Values", "Joe Gould's Secret", "Drunks", "Small Time Crooks", and "Celebrity".

Halston first achieved fame through her performances in the comedies of writer-performer Charles Busch, including Vampire Lesbians of Sodom (1985) and The Lady in Question (1989). She performed in a series of one-woman comedy shows in the 1990s. Other theater credits include Broadway productions of The Man Who Came to Dinner (2000), The Women (2001), Hairspray (2002) (replacement Female Authority Figure), Gypsy (2003), Twentieth Century (2004) and Anything Goes (replacement "Evangeline Harcourt", January 2012). Her performances in the Off-Broadway play White Chocolate (2004) and Busch's Red Scare on Sunset (1991) both earned her Drama Desk Award nominations for Outstanding Featured Actress in a Play. In 2013, Halston appeared as Rita in the Primary Stages production of The Tribute Artist.

She has won four MAC Awards (Manhattan Association of Cabarets & Clubs) for her solo comedy performances and Characterization/Monologue (1996). She performs her comedy act "Classical Julie" at Birdland in July 2012.

She married Ralph Howard in 1992. At the time, he was an anchor and entertainment reporter for WINS Radio. Howard worked for Howard Stern radio from 2005 to 2013. She has 5 step-children and 10 step grandchildren. They include the Herzig family and the Howard family.