Whitehead rose to prominence after competing in the third round on the first season of Australian Idol in 2003. His debut extended play, The Axle Whitehead Band, was released as a collaboration in 2003 with jazz fusion band, the Axle Whitehead Band (feat. Steve Sedergreen, piano & keys). The release failed to rank on national charts. Whitehead released his debut studio album, Losing Sleep, in 2008 on Roadshow Music. The album peaked at number 68 on the Australian Top 100 Albums Chart. The lead single "I Don't Do Surprises" debuted at number eight on the Australian Top 100 Singles Chart and received gold certification by the Australian Recording Industry Association. The album's subsequent singles "Anywhere" and "Satellite" did not make it into the Top 50.

In October 2006, Whitehead was sacked as TV presenter of Video Hits after exposing himself on stage during the ARIA music awards. Axle was onstage to present an award to Aussie hiphop band The Hilltop Hoods when he exposed himself and simulated masturbation on the trophy, though it wasn't aired on TV.

Whitehead's debut single "I Don't Do Surprises" was released on radio during January 2008, debuting at #8 on the ARIA Charts in Australia on 17 March 2008. Also reaching No.1 of Australian ITunes charts. It has also received airplay on Nova radio and surfaced on TV advertisements for popular Channel 10 shows House and Women's Murder Club, and Channel 7's Home and Away, being described as a cross between Coldplay and Robbie Williams. His debut album, Losing Sleep was mixed by UK mixer, David Treahearn and released through Roadshow Music on 22 August 2008. Whitehead made his return to Video Hits on 24 February 2008, and to Australian Idol on 5 September 2008, though only as a guest to promote his debut album. The third single off Losing Sleep, Satellite has received significant play on Channel V and Video Hits.

On 22 April 2009, Whitehead was announced Cleo Bachelor of the Year, beating competition from sportsmen, actors and other personalities. Sarah Oakes, Cleo Editor-in-chief denied the claims that Whitehead won as a direct result of a self-marketing ploy; "[He] is that perfect combination of good looks, charm, charisma and the kind of guy you'd be really happy to take home and introduce to your mum."

Whitehead hosted Seven Network's The World's Strictest Parents. In 2010, Whitehead was short-listed to host The X Factor Australia, but lost out to fellow Home and Away colleague Luke Jacobz.

Whitehead departed Home and Away in late 2012 to expand his acting career. He filmed his final scenes along with colleague Luke Mitchell (Romeo Smith). Whitehead moved to Los Angeles. After 18 months as an out of work actor, he landed a role in season 5 of the critically acclaimed series Shameless. He played an Australian rock singer named Davis, a love interest of Fiona Gallagher (Emmy Rossum). He appeared in the first 4 episodes of season 5 and a brief appearance in episode 8.

In 2014, Whitehead was the runner-up for the Heath Ledger scholarship. In 2016, he played James Slade / Hellfire, a recurring role in Agents of S.H.I.E.L.D.. This role reunited him with Home and Away star Luke Mitchell.

In 2017, Whitehead began hosting Australian game show The Wall, which is based on the U.S. show of the same name.