Born in Sydney, he began his playing career with the New South Wales Institute of Sport before moving to England to join Everton.

Having failed to break into the Everton first team he then moved to Oldham Athletic, Halifax Town and Hamilton Academical in Scotland before returning to his native Australia.

After a successful spell with Sydney FC in A-League, Carney then returned to England, signing with Sheffield United before spending time with Norwich City on loan and eventually moving to the Netherlands to play for Twente.

He subsequently had spells with Blackpool, AD Alcorcón, Bunyodkor, Newcastle Jets and New York Red Bulls as well as making 48 appearances for the Australia national side for whom he scored six goals.

Carney trialled for newly formed A-League side Sydney FC in March 2005 and was signed to a one-year deal after impressing coach Pierre Littbarski.

On 16 December 2005, Carney scored the winning goal against African champions El Ahly to secure Sydney FC 5th place at the tournament.

His dribbling and occasional goal poaching made Carney a genuine crowd favourite at Sydney FC and he subsequently attracted the attention of a number of clubs in Europe.

[6] Despite scoring twice in a trial match and being offered a deal by Aachen he decided against signing for the club, citing "the language factor" as the main reason for declining the move.

These performances and his displays in the Australian national team reportedly led to interest from German clubs Bayern Munich, VfL Bochum and Kaiserslautern; and a £2.3 million bid from Belgian champions Anderlecht.

In August 2009 Sheffield United agreed to the sale of Carney to Dutch Eredivisie side FC Twente[13] in what was reported to be a two-year deal with a third year extension option.

[18] On 18 February 2012, the club signed Carney to play in the 2012 Uzbek League, which runs from March to September with a possible return to the A-League for the 2012–13 season.

[23] It was finally confirmed on 29 September, that Carney was released from the club after spending weeks without playing for the team and chasing money owed to him.

[26] Carney signed with Major League Soccer club New York Red Bulls on 8 August 2013, a move that reunited him with Australian international teammate Tim Cahill.

[32] On 2 February 2016, about 7 hours before the transfer window in Australia ended, it was announced that Newcastle Jets had agreed to release Carney by mutual consent.

Carney chose to play for Australia in the 2008 Summer Olympics, rather than staying in the UK to concentrate on the forthcoming season with Sheffield United.

[37] During the Asian Cup championship, Carney was selected to play in the starting line-up for Australia against co-host nation Thailand in the final game of the group matches.

He scored the second goal in their 2–0 victory in Sydney and was then rested for the final group game against Japan in Melbourne the following week due to being on a yellow card.

In the final against Japan, an error made by Carney in extra-time allowed Japanese player Tadanari Lee to volley the winning goal.