After appearances in numerous forgettable B-movies like 1987's Campus Man and 1991's Body Parts, as well as TV's Tales from the Crypt and several episodes of L.A. Law's 1987 season, she got the role of a lifetime on ABC's new police drama, NYPD Blue, in 1995. Delaney was hired to portray Detective Diane Russell for four episodes of the second season of NYPD Blue, but by the time she had filmed two episodes, the producers of the show were so impressed that they asked her to join the series full-time. Her credibility in the role of Detective Diane Russell earned her an Emmy for Best Supporting Actress in 1997, as well as nominations in the same category in the two years that followed. After six years with the long-running controversial cop drama, she finally hung up her detective gear in 2001.

After Delaney starred in the short-lived and relatively unsuccessful, Philly (also a Bochco production) on ABC, she joined the cast of the new CBS show, C.S.I.: Miami, a spinoff of the highly successful C.S.I.. Her role as a forensic scientist and DNA specialist lasted 10 episodes. CBS insinuated that she left the show because her character was hastily added and was no longer integral to the plot, although rumors abound about whether or not difficulties with David Caruso may have played a role in her departure.

Delaney doesn't mind discussing her pastimes, which include swimming, working out, and spending quality time with her family and friends, but she remains tight-lipped when it comes to other personal details, perhaps because of her numerous marriages (she was divorced twice, most recently from actor Joseph Cortese, and is now remarried to her third husband), and her arrest and subsequent prosecution for driving under the influence in early 2002. After the highly publicized incident, she was given two years' probation, slapped with a $300 fine, and ordered to attend a safe driving class. Delaney currently lives in Los Angeles in the posh suburb of Beverly Hills, California, with her son Jake and television producer Alan Barnette. As for her career, her most recent big-screen role was in 2000's Mission to Mars.