Boyd started his career in the youth academy at Charlton Athletic, before joining Stevenage Borough of the Football Conference in 2001.

A loan move to Hull City followed for the remainder of the 2012–13 season, helping the club earn promotion back to the Premier League during the three-month agreement.

[6][8] Boyd made his Stevenage debut at the age of 17 during the 2002–03 season, playing the first half in a 3–1 defeat against Margate at Broadhall Way on 14 December 2002.

[17] Under the new management of Mark Stimson ahead of the 2006–07 season, Boyd was deployed in a more central role for the first time in a 2–1 defeat away at Tamworth on 2 September 2006, a match in which he scored Stevenage's solitary goal.

[4][26][27] Boyd made his debut for Peterborough in a 3–1 defeat away at Darlington on 13 January 2007,[28] and scored his first goal for the club a month later in a 3–0 win against Wrexham on 10 February 2007.

[35] Boyd played in Peterborough's first match of the 2009–10 season, marking his first appearance in the second tier of English football, scoring from the penalty spot in a 2–1 defeat to Derby County at Pride Park.

[36] Boyd made a club record-equalling 124th consecutive appearance on 17 October 2009, scoring a last minute equaliser against Bristol City at Ashton Gate.

[43][44] The following day, Peterborough United director of football Barry Fry confirmed that Middlesbrough were in transfer talks over Boyd, although ultimately the two clubs failed to agree a fee for the player.

[46] After Boyd's proposed move to Middlesbrough fell through, he joined fellow Championship club Nottingham Forest on loan on 2 March 2010, on an agreement until the end of the 2009–10 season.

[73][74] At the end of that season, Boyd rejected the offer of a contract extension at Peterborough with one year remaining on his current deal.

[79] In January 2013, Peterborough rejected a transfer bid from Nottingham Forest for Boyd,[81] an offer that club chairman Darragh MacAnthony described as "derisory".

[85][86] A day later, several other Championship teams had improved transfer bids accepted,[87] including Nottingham Forest, who met Peterborough's £500,000 valuation.

[91] Boyd said in 2020 that he had chosen Nottingham Forest over his childhood club Crystal Palace as he was looking to settle in the East Midlands following the birth of his child.

[55] Boyd subsequently joined Championship club Hull City on loan until the end of the 2012–13 season on 21 February 2013, with a view to a permanent move.

[92] He made his debut two days after signing, coming on as a second-half substitute for Robert Koren in a 4–1 away defeat to Bolton Wanderers.

[97][98] He made his Premier League debut on the opening day of the 2013–14 season when he came off the substitute's bench in a 2–0 loss against Chelsea at Stamford Bridge.

[104] The start proved to be only one of two appearances for Hull during the opening month of the season as manager Steve Bruce stated Boyd was nearing a move to fellow Premier League club Burnley.

[107] The move to Burnley was confirmed on 1 September 2014, Boyd signing for an undisclosed fee "believed to be in the region of £3million" and on a three-year contract.

[108] Boyd scored his first goal for Burnley in the club's 3–1 defeat to West Ham United at Turf Moor on 18 October 2014, briefly halving the deficit when he reacted the quickest to latch onto Michael Kightly's cross.

[112] Boyd proceeded to score in the corresponding home fixture against Manchester City on 14 March 2015, his fifth goal of the season, when he "arrowed in a low half-volley" to secure a "famous" 1–0 win.

[117] Boyd's first-half goal in Burnley's 2–1 away win at Birmingham City on 16 April 2016 helped move them to within two points of the top of the Championship.

[120] Boyd started in Burnley's first game back in the top flight to open the 2016–17 season, playing the whole match in a 1–0 home defeat to Swansea City.

[107] Boyd subsequently signed for Championship club Sheffield Wednesday on a free transfer on 3 July 2017, joining on a two-year deal until 2019.

[130] Boyd suffered a shoulder injury in September 2017 that was initially described as "nothing serious",[131] but would ultimately require two separate surgeries and keep him out of the first team for four months.

[142][143] He was released by the club on 13 October 2020, with Boyd stating he was "gutted" his time at Peterborough had concluded, as well as feeling frustration at not being able to play due to the new salary constraints.

[140] After his departure from Peterborough, Boyd signed a contract with League Two club Salford City on 3 November 2020, with the agreement running for the remainder of the 2020–21 season.

[144] He made his Salford debut in the club's 2–1 away defeat to Cambridge United on the same day as his signing was announced, coming on as a 70th-minute substitute in the match.

[151] Boyd was called up for the Scotland B team on 30 April 2009, after obtaining documentary proof that his maternal grandfather was born in Glasgow.

[155] Boyd received his first call-up to the senior team on 7 March 2013,[156] when he was named in manager Gordon Strachan's squad for the 2014 FIFA World Cup qualifiers against Wales and Serbia.

[5] He has expressed his willingness to "play anywhere" to help the team, believing his versatility across the midfield and attacking areas to be one of his main strong-points.