Hazell was born on 24 November 1987 in Essex. His father Paul (who died from Motor Neurone Disease in 2010) worked as a financial analyst, while his mother worked part-time at a residential care home. At the age of five Hazell made his stage debut in a school nativity play. At the age of twelve he landed the part of Michael in an original community play called Down the River and Up the Road at the Queen's Theatre, Hornchurch. After gaining his GCSE's, he attended Barking and Dagenham College
Aged 17, Hazell appeared in his first feature film Flyboys (2006), which received critical acclaim. Since then Hazell has appeared in police drama The Bill twice and the British series Law & Order: UK in early 2009. In America he has starred in sci-fi horror TV film Croc (2007). He has also guested in many popular US shows, including Genie in the House (2008). Some argue that his best TV work was as David Phillips in the acclaimed docu-drama A Walk into Hell, an episode in season 2 of the series I Shouldn't Be Alive (2006) with Aaron Johnson.