He began his career with non-League side Great Harwood Town before earning himself a move to local Premier League team Blackburn Rovers in 2003.

He played for Blackburn for five years, and had loan spells with Plymouth Argyle, Wrexham and Olympiacos, before joining the latter club on a permanent basis in 2009.

He returned to England in 2010 with Birmingham City, and continued with spells at Nottingham Forest, Oldham Athletic, Blackpool and Rotherham United.

[4] He progressed through the youth and reserve teams, and his performances earned him the Supporters' Young Player of the Year award for the 2004–05 season.

[6] He joined Championship club Plymouth Argyle on 30 August 2005 on loan for the season;[7] a few days later, manager Bobby Williamson was sacked.

[16] He also scored against Manchester United, taking advantage of a defensive error to give Blackburn Rovers a 1–0 lead, although they went on to lose the match 4–1.

[21] He found starts hard to come by under new manager Paul Ince and played little after the arrival of his successor Sam Allardyce,[21][22][23] and in late January 2009, Derbyshire joined Olympiacos on loan until the end of the 2008–09 Superleague season.

In the return match, his home debut, Derbyshire scored a goal in extra time, securing progress to the semi-finals.

However, with the last touch of the game, Derbyshire headed an equaliser in the sixth minute of added time, bringing the score to 3–3, after having suffered a broken nose and suspected concussion following a clash with an opponent.

[27] On 21 March 2010, Derbyshire scored the winning goal against Panathinaikos, in a 1–0 away victory, and was instantly nicknamed The English Killer by the Greek media.

[29] Derbyshire returned to England when he signed for Birmingham City on 16 August 2010 on loan for the 2010–11 Premier League season, with a possibility of the deal being made permanent at the end of that time.

[32] After waiting until January 2011 for his first Premier League start for Birmingham, against Blackpool, he then scored twice in the 4–1 win at Millwall in the third round of the FA Cup.

At Forest, Derbyshire renewed acquaintance with assistant manager Rob Kelly, who was his coach when he was a youth player at Blackburn Rovers.

[50] He made his debut on 30 June against FC Banants Yerevan in the first leg of the Europa League first qualifying round, and scored the only goal of the match.

[52] On 4 January 2017 he drew attention when he scored a hat-trick against Ethnikos Achna in 4 minutes, overturning a 2–0 deficit against Omonia, that gave his side a valuable league victory.

[59] On 10 July 2021, Macarthur FC confirmed that they had agreed an undisclosed fee for Derbyshire's transfer to Cypriot top-flight club AEK Larnaca.

[67] Derbyshire was called up to the England Under-21 squad by new manager Stuart Pearce for a friendly against Spain on 6 February,[68] but was forced to withdraw after he tore a thigh muscle playing for Blackburn three days before the match.

[69] However, Derbyshire was fit enough to be included in the under-21 squad to face Italy in the opening fixture of the new Wembley Stadium on 24 March; he scored England's third goal in a thrilling 3–3 draw.