Born in Leeds, West Yorkshire, Monkhouse began his career with Rotherham United as a trainee before rising to the senior ranks at the age of 18 and scored on his début in a 3–0 win against Hartlepool United. After 128 league outings for Rotherham and a couple of long-term injuries, in May 2006 Monkhouse was released.
Swindon Town
Monkhouse became Dennis Wise's first signing as manager of Swindon Town on 22 June 2006, signing a one-year contract.
Hartlepool United
Monkhouse's time at Swindon was interrupted by injury and he was loaned to Hartlepool United. Following a successful loan spell, a deal was then agreed between Swindon and Hartlepool United on 10 January 2007. Remarkably, the first time he was on the losing side in a league match in 2006–07 was in United's defeat against Barnet on 7 April 2007. Monkhouse was named in the PFA League TwoTeam of the Year for the 2006–07 season after Hartlepool went on to finish 2nd to secure promotion to League One. After playing in a 1–0 win against Sheffield United in the Football League Trophy in October 2013, Monkhouse made his 300th appearance for Hartlepool in all competitions, which made him one of only 16 'Pools' players to do so. Monkhouse was released in May 2014, ending a seven-year stay with the 'Pools'. He played in 331 games in all competitions for the North-East and is currently eleventh in Hartlepool's all-time appearances list.
Bristol Rovers
On 21 July 2014, Monkhouse signed for Bristol Rovers on a one-year deal after being released by Hartlepool United. He helped the club earn an instant return to the Football League, being a part of the team that gained promotion by winning the 2015 Conference Premier play-off Final. Monkhouse left the club on completion of his contract as he sought a club closer to his Leeds home.
Grimsby Town
On 24 June 2015, Monkhouse signed for Conference National side Grimsby Town on a one-year deal. Monkhouse was a regular player in the squad that eventually gained promotion with Grimsby's 3–1 victory over Forest Green Rovers in the 2016 National League play-off Final at Wembley, seeing Grimsby promoted to League Two after a six-year absence from the Football League. Monkhouse was released when his contract expired at the end of the season.
Alfreton Town
Monkhouse signed for National League North side Alfreton Town upon his release from Grimsby. He scored 6 times in 46 appearances as Town narrowly avoided relegation. In February 2017, Monkhouse took up the role as Alfreton's player/assistant manager.
Whitby Town
On 7 July 2017 he signed a one-year deal with Northern Premier League side Whitby Town. Monkhouse played at centre-half for Whitby and made 52 appearances for the club.
Monkhouse holds a UEFA A Licence and is currently an academy coach with his former club Rotherham United, as well as being in a player/coach role at Ossett United. Monkhouse was previously player/assistant manager at Alfreton Town.
