Born on 21 August 1979 in Sydney, Australia, Griffiths represented Australia at the FIFA World Youth Championship in Nigeria in 1999.

He made his way through Australia's club system with spells at Sydney United, Parramatta Power and Newcastle United Jets. In 2001/02 he scored ten goals in 24 games for the Jets, adding 18 in 21 the following season. That record won him a move to Switzerland with Neuchatel Xamax in 2003.

He made his debut for Australia in a friendly against Jamaica in October 2005, scoring in the 5-0 win.

Griffiths cost Leeds £28,000 from Neuchatel when he signed an 18-month contract in January 2006, but he was forced to return to his native Australia sort out his settlement visa for the United Kingdom in February.

Griffiths' move to Elland Road was marred by a spat with Neuchatel that rumbled on for three weeks after he signed for Leeds. Griffiths had turned down offers of higher wages and higher divisions to join Leeds' promotion challenge, only for Neuchatal to delay the move over demands for compensation. Leeds had won an appeal with FIFA, lodged through the FA, for the forward's clearance, yet nothing budged.

Griffiths' Leeds debut came when he replaced Eddie Lewis for the final 17 minutes when Leeds drew 0-0 at home to Stoke on 25 March. He had scored for the reserves in midweek, but was less successful against Stoke, having a shot saved. He also came on in United's final fixture, a meaningless game against Preston, but it was clear that Blackwell did not rate him and he was gone within weeks, returning to Newcastle Jets for an undisclosed fee.

Griffiths complained, 'I played a handful of games. It just didn't work out with me and the gaffer there. I don't regret leaving Switzerland [but the manager] tried to play me into a system where I wasn't quite used to the right wing position and the way he wanted me to defend. He paid a transfer fee for me, and he was, like, crucifying me.'

He did well with the Jets in 2006/07, scoring six goals as they finished third. His twin brother Adam joined the club the following season, but Joel was fined two weeks' wages after assaulting a linesman. Nevertheless, he won the A-League Golden Boot award after scoring twelve goals and taking the Jets to runners-up spot.'

Things went awry after that and Griffiths moved on loan deals to Japan and China. He refused to attend training when he returned to the Jets and moved to Beijing Guoan after a successful spell on loan. He moved on to Shanghai Shenhua in January 2012 and then signed for Sydney FC in December 2012.

In 2012, he was suspended for three matches after abusing an assistant referee and was sacked from his second spell with Newcastle Jets after being part of a player revolt against manager Phil Stubbins following a 7-0 defeat to Adelaide. His pièce de résistance remains punching a linesman in the 'midriff', for which he escaped a ban because he was booked by the referee at the time.

He returned to China with Super League club Qingdao Jonoon after being released by Sydney in July 2013 and then returned to the Jets in January 2014. He was sacked after a players' revolt and took a short-term contract with Wellington Phoenix, He played for Lambton Jaffas from 2017 to 2019 and ended his playing career at Newcastle Olympic, where he became club coach.

In 2023, Griffiths was suspended for five matches after Northern NSW Football banned him for calling Broadmeadow's Uruguayan keeper Cesar Serpa 'a f***ing terrorist'. He was sacked in July of that year.