Born Simone Nicole Jean Lahbib Ould Cheikl on 6 February 1965 in Stirling, Scotland, to a Scottish mother and a French Algerian father. She received her acting training at Queen Margaret College in Edinburgh after four years at The Manor School of Ballet in Edinburgh. One of her first performances was playing the part of Cathy in Wuthering Heights in rep at the Brunton Theatre in Musselburgh.

Following her 1985 film debut, Lahbib did not appear in a feature film until 2005's Red Mercury, with Stockard Channing, and from 2013, she has frequently been appearing in films such as the award-winning Philomena, with Judi Dench, Wayward's Song, Film: The Movie, which was directed by her husband, Raffaello Degruttola, as well as being co-produced by herself and the 'making of' of the film was also produced by Lahbib. She will appear in the upcoming film Detour.

It was not until 1999 that Lahbib became widely recognized for her leading role in the cult British prison drama series Bad Girls, for which she played Helen Stewart, the new G-wing governor who tries to help the prisoners and make G-wing a better place, although, she doesn't receive the help she expects for the officers, she enlists the help of prisoner Nikki Wade and from there a personal relationship develops. Lahbib appeared in Bad Girls until the end of the third series when Helen and Nikki eventually get together following Nikki's release from prison. For her role as Helen Stewart, Lahbib has established a loyal fan base throughout the world, especially among the lesbian community. Following her departure from Bad Girls, Lahbib has appeared in several drama series including Judge John Deed and Monarch of the Glen and was again cast in a leading role on the crime drama series Wire in the Blood as D.I. Alex Fielding. She appeared in the role from series four to series six when the series was cancelled. Lahbib's other television credits include guest appearances in New Tricks and Downton Abbey.

Lahbib married British-Italian actor Raffaello Degruttola on 10 May 2003 in her hometown of Stirling, Scotland. In October 2005, she gave birth to their daughter, Skye. In 2010, Lahbib established the Eilidh Brown Memorial Fund in honour of her niece who died of cancer on 25 March 2010, nine days before her 16th birthday. The charity fund will benefit children with cancer and their families.

In 2013 Lahbib opened a part-time performing arts school 360 Arts in North London, which teaches singing, dancing and acting to children aged 3-18 years at the Bull Theatre in Barnet.