Hazell was born on 18 September 1986 in Lewisham, London, England, and grew up in Grove Park. She attended the Ravensbourne School in Bromley. Her mother, Amber, was a dinner lady, and her father, Roy, was a window fitter; they separated when Hazell was 13 years old.

At 16 years of age, Hazell left school to work as a hairdresser. Her colleagues persuaded her to try her luck at modelling. At 17, she competed in The Daily Star's "Search for a Beach Babe" contest and won. Still not old enough to pose on Page 3, she went to study fashion at Lewisham College. Later, a friend told her about The Sun's Page 3 Idol competition. Despite some initial uncertainty about entering the contest, she submitted some photos. She was eventually chosen the winner in December 2004. She won £10,000 worth of "sexy clothes" and "a one-year membership of the Rex cinema and bar". Another part of Hazell's Page 3 Idol win was a one-year exclusive glamour modelling contract with The Sun.

In June 2005, Hazell appeared on the front cover of Maxim magazine, and she also appeared on the front cover of FHM in September 2005. In January 2006, she appeared on the front cover of Loaded magazine.

Hazell was hailed by Conservative leader David Cameron in December 2006 as an "environmental hero" for her campaigns in The Sun, giving environmental tips such as turning Lights off during the day. She was named alongside the likes of David Attenborough, Prince Charles, and Arnold Schwarzenegger in the Tories' list.

In 2007, Hazell and IT expert Gary Schwartz co-presented Byte Me TV, an online programme that tried to explain Technology in an easy-to-understand way.

Hazell released a pop music single called "Voyeur" in 2008.

In 2009, according to the August edition of Loaded, Peta Todd stated that Hazell had given modelling up to pursue a career in acting and that she was in America receiving acting lessons. Her last appearance on Page 3 of The Sun was on 30 September 2009.

In 2010, Hazell had her first lead role in the short film Venus and the Sun, a comedic retelling of Ovid's myth, Venus and Adonis.

Hazell had a small role in the film Like Crazy, which won both the Grand and a Special Jury Prize at the 2011 Sundance Film Festival.

In 2012, Hazell played a supporting role in the British gangster movie St George's Day, which was directed by Frank Harper. In 2015, Hazell landed a role in E!'s first scripted drama, The Royals, as "Violet".

Hazell starred in the 2013 comedy film Awful Nice and the 2015 horror film Whispers. She also appeared in the 2016 short film Queen of Hearts.