Born Kelly Parsons on November 23, 1979, in Rochester, Kent, England, she is the daughter of Sandra, a cook, and Ken, a scaffolder. Ken Parsons died from cancer in November 2007, during Brook's time on Strictly Come Dancing.
Kelly attended The Thomas Aveling School in Warren Wood, Rochester, Kent. After leaving school in Rochester, Brook studied at the Italia Conti stage school in London for three years before becoming a professional model.
After graduating, she pursued dance and went on to appear in numerous pop videos. Shortly thereafter, Kelly caught the eye of a photographer who introduced her to a modeling agent. In only a few short years Kelly went on to become one of the most recognized models in Britain.
Eager to move on from the modeling world and back to her greatest love, performing, Kelly was eager to try something new. The Big Breakfast was a popular live morning show that was looking for a host. After beating off stiff competition from more experienced peers, she landed the job after turning just eighteen. This made front page news, turning Kelly into a national treasure overnight. After such a high profile stint she signed a deal with MTV to host her own show for the music television network. During this time Kelly landed a couple of roles in small independent movies, which gave her her first feature experience.
Confident in her ability as an actress, Kelly set out on her journey to Hollywood. After just three weeks she landed her first role in the Warner Brothers project, The Miss Adventures of Fiona Plum. Kelly played the title character, a British witch sent to America to become a nanny. Keen to remain in business with Kelly, Warner Brothers offered her a role in a new show called Smallville. Kelly played the role of Victoria Hardwick in what Rolling Stone cheekily described as "the best episodes of Lex Luther's life.”
Brook's modelling career began at 16 after winning a beauty competition her mother entered her in. Following this success she worked on a range of advertising campaigns, including for Foster's Lager, Renault Megane, Walkers crisps, Piz Buin and Bravissimo, a company that specialises in bras and lingerie for large-breasted women. Her voluptuous figure eventually caught the eye of the editorial team of the Daily Star tabloid, which began featuring her as a Page Three girl.
Brook's picture soon began appearing in other lad mags such as GQ, Loaded and FHM. In April of the same year a poll over 5,000 women for Grazia magazine considered her to have the best British female body. She also topped the 'FHM 100 Sexiest Women in the World' list in 2005, which was said to have polled 15 million people. She later ranked 5th in FHM's '100 Sexiest Women in the World 2006', 17th in 2007 and 34th in 2008 respectively.