Born in Leicester, Joe Mattock started his career with his hometown club making his professional debut for Leicester City in 2007. His talent was spotted at an early age by his country, earning him caps for England at under 17 and under 19 levels as he began to make his way in the professional game. At the back end of the 2006/7 season he made a further three appearances for the Foxes in The Championship, which included his first start in a 2-1 home defeat to Birmingham City.
Mattock became a regular in the Leicester side during the 2007/8 season but he couldn’t help prevent Leicester being relegated to League One. Relegation proved to be only a minor stumbling block in his career, and after 36 appearances in all competitions he was a vital component in the Leicester side that comfortably won the League One title in 2009.
During the title winning campaign he also scored his first professional goal in a 2-0 victory at Yeovil Town. In August 2009 he earned a million pound plus move to West Bromwich Albion and helped the Baggies to promotion to the Premier League after finishing runners up. During this time Mattock made several appearances for the England under 21 side.
That would be the highlight of his career at West Brom, as he was given little opportunity in the Premier League. Mattock joined Sheffield United on loan where he made 13 appearances, and the following season he also enjoyed loan spells at Portsmouth and Brighton. In 2012 he joined Sheffield Wednesday on a free transfer, signing a three year deal with the Owls.
After making over 50 league starts for Wednesday he left Hillsborough and joined the Millers on a two-year deal.
Last season he was a consistent figure under three managers, playing 36 games in all competitions and scoring a spectacular goal in the defeat at Brentford.