Humphrey announced his retirement from football in October 2018, due to ongoing injury problems before returning to the game with East Kilbride.

[5][6] Three days after signing, on 9 September, Humphrey made his debut as a 79th-minute substitute for Ben Herd in a 1–0 home defeat to Lincoln City.

[7] On 8 February 2007, and having made nine substitute appearances, Humphrey's progress had pleased Peters sufficiently to earn him a one-year contract extension until summer 2008.

After making three league and three cup appearances in the early part of the 2007–08 season Humphrey joined Conference National side Stafford Rangers on 2 November 2007 on loan for a month, playing four games.

[9] He scored his first goal on 25 October 2008, two minutes after coming on as a 78th-minute substitute for Shane Cansdell-Sherriff to earn Shrewsbury a 1–1 draw with Brentford at Griffin Park.

[10] Late in the January 2009 transfer window, and with Humphrey about to be out of contract in summer, it was claimed that he had attracted the interest of various clubs, including Aston Villa, following a number of eye-catching performances that season.

[11] On 2 May, Humphrey set up one goal and scored another as Shrewsbury beat Dagenham & Redbridge 2–1 to ensure the Shrews finished in seventh place in League Two, the fourth and final play-off spot.

[14] On 25 June 2009, Sky Sports claimed that Shrewsbury had turned down a bid for Humphrey by Championship side Blackpool.

[22] His league debut for the club came on the opening day of the season, as a half-time substitute, in a 2–2 draw against St Johnstone.

In September 2009 after Humphrey and his partner suffered personal tragedy, Motherwell gave him several weeks' compassionate leave.

[25] Having found it difficult to gain a regular place in the team, the January transfer window saw a number of English clubs linked with a loan move for Humphrey.

[27][28] Having begun to nail down a regular place in the team, Humphrey scored his first goal for Motherwell, just three minutes into a 3–1 win against St Mirren.

[30][31] A few months later, on 30 March 2011, he scored his second goal of the season, in a Scottish Cup quarter-final replay against Dundee United, which Motherwell won 3–0 to send the club through to the semi-final.

This gave the club qualification to the Champions League qualifying rounds, due to second placed Rangers being in administration, preventing them from taking part.

[42] On 4 June 2013, it was announced that Humphrey would be leaving Motherwell to join Preston North End on a three-year contract.

[51] Humphrey continued to play regularly for Preston during 2013–14 and 2014–15, and the club gained promotion from League One to the Championship in the latter season.

[52] Humphrey featured less frequently in the team when it was in the Championship, and he left Preston North End on 30 December 2016 when his contract was terminated by mutual consent.

[52] Humphrey returned to Scottish football on 31 December 2016, signing a contract with Championship club Hibernian until the end of the 2016–17 season.

[54] Humphrey suffered a calf injury in a Scottish Cup tie with Hearts in February, which caused him to miss nine first team matches.

[63] Due to the COVID-19 pandemic, Kelty were declared Lowland League champions on 13 April 2020 on a points per game average based on the current standings.