Born in Boston and raised in Newport, Rhode Island and Amherst, Massachusetts, Koslow wanted to be an actor even as a young age. After graduating with a theatre degree specializing in costume design from Virginia State University, Koslow signed on with a summer stock theater group in Virginia as a costume designer. She was also asked to audition for the role of Vera in the play Ten Little Indians.
Koslow soon put her costume designing talent aside to become a full-time actress, appearing in such regional productions as Cat on a Hot Tin Roof, Dial M for Murder, and The Importance of Being Earnest. She then moved to Los Angeles to pursue a television career and landed roles on such shows as The New Mike Hammer, House Calls, Spies, and The A-Team.
While in an acting class, Koslow met a producer from The Young and the Restless who encouraged her to audition for his series. Koslow not only won the role, but found her husband, make-up artist Nick Schillace, on the show. Koslow was then cast as fashion designer Margo Lynley on The Bold and the Beautiful. Following this role, Koslow was cast as Kate Roberts on Days of our Lives.
Koslow is the proud mother of two, Zachariah, and Milikate. When she's not working, Koslow enjoys traveling, painting and encouraging her children to take care of the mini family zoo. They have three lizards (two bearded dragons and one spotted gecko), a talking parrot named Charlie, three dogs named Peggy Sue, Buddy, and Murphy McMuffin, a cat named Frankie and a few horses in their menagerie.
In 2001, Koslow was nominated as Outstanding Supporting Actress for the Soap Opera Digest Awards.
Koslow and her family recently moved to a more rural area of Ventura County, just north of Los Angeles. Her birthday is March 9.