Aberdeen Maguire made his debut for Aberdeen on 7 May 2006, coming on as a substitute in their final match of the
2005–06 season, where he set up
John Stewart for the equaliser in a 2–2 draw against SPL champions
Celtic. His first starting appearance in the senior team was on 26 December against
Kilmarnock, where he also scored his first senior goal in the sixth minute. The following season, Maguire scored some vital goals, including a 94th-minute winner in a thrilling 4–3 match against
Inverness CT on 29 March 2008 and a brace in the 2–1 win over
Falkirk five days later. On 16 July 2008, Maguire signed a three-year contract extension with the Dons. In February 2009, having been regularly kept out of the starting eleven by first-choice striking pair
Darren Mackie and
Lee Miller, Maguire requested to go out on loan in search of regular first-team football. After this request was promptly turned down, Maguire scored two goals in Aberdeen's 5–0
Scottish Cup victory over
East Fife.
Kilmarnock (loan) During the January transfer window in 2010, Maguire moved on loan to
Kilmarnock, reuniting him with former Aberdeen boss
Jimmy Calderwood. On his debut against
Celtic, he scored the only goal of the game to give Kilmarnock their first league win in eight games. Maguire's form after signing saw him win the
Scottish Premier League Young Player of the Month award for February 2010. He scored 4 goals in 14 games to help Kilmarnock stay in the Scottish Premier League.
Derby County On 1 June 2011, it was announced Maguire would sign for
English Championship side
Derby County on the expiration of his Aberdeen contract, having agreed a three-year deal with Derby. The transfer was formally completed on 29 June when Derby agreed a compensation package with Aberdeen, speculated to be in the region of £400,000. Maguire's first start, and first goal, came on 29 October, in a 3–1 win over
Portsmouth. He was subsequently praised for his patience and work ethic by first-team coach
Andy Garner, having been kept out of the team by the form of fellow strikers
Jamie Ward,
Theo Robinson and
Steve Davies. However, he failed to cement a place in the first team, finding himself behind strikers
Theo Robinson,
Steve Davies,
Jamie Ward and youth product
Callum Ball. Maguire scored a hat-trick against Pinxton in a 4–0 win during the quarter-final of the
Derbyshire Senior Cup.
Portsmouth (loan) On 9 March 2012, Maguire joined Championship strugglers
Portsmouth on a month-long emergency loan. He wore the number 22 shirt during his time at Fratton Park. Maguire scored his first Portsmouth goal in his side's 4–1 victory over
Birmingham City at
Fratton Park on 20 March 2012. Maguire received praise from Portsmouth manager
Michael Appleton for his role in a 2–0 win against
Hull City on 27 March 2012 and hoped for an extension to his loan. After one month at
Pompey, the club extended Maguire's loan until the end of the season. Maguire impressed for Portsmouth where he scored 3 goals in 11 appearances, and picked up the club's Player of the Month award in the game against parent club Derby County (a game which Maguire was ineligible to play in) on 21 April 2012, a game which saw Portsmouth relegated in a 2–1 defeat.
Sheffield Wednesday On 22 May 2012, Maguire was transfer-listed by Derby.
Sheffield Wednesday, newly promoted to the Championship, had two bids rejected to buy Maguire in May 2012 but on 21 June 2012, they announced that Maguire had joined them on a three-year deal. He made his Owls debut in the 4–2 League Cup win over
Oldham Athletic on 13 August. However Maguire had to wait until 16 March 2013 for another league appearance in the 0–2 defeat against
Cardiff City. When right midfielder
Michail Antonio was brought down and injured, Maguire came on as substitute. Maguire made his second league appearance, again as substitute, in the 2–1 victory against South Yorkshire rivals
Barnsley. Maguire made a fourth appearance for the Owls in a 3–2 victory over
Blackburn Rovers, replacing
Jermaine Johnson in the 84th minute. Maguire came on as substitute and grabbed a late six-yard goal in the 92nd minute in his first goal for the Owls against
Millwall in 2–1 away victory on 9 April 2013. Maguire scored his first goal of the
2014–15 season against
Millwall, a 57th-minute free-kick with the game ending 1–1. Maguire had to wait until 4 October 2014 for his second goal of the season, a thunderous strike against local rivals
Leeds United in the 52nd minute with the game ending 1–1. Maguire's third goal of the season came against
Blackpool on Boxing Day, a 39th-minute penalty which proved to be the winner in a 1–0 victory. On 10 January 2015, Maguire scored his fourth goal of the 2014–15 season at
Nottingham Forest in Wednesday's 2–0 victory and followed that up the following week with a penalty against
Bolton Wanderers in a 2–1 defeat. On 4 March 2015, Maguire scored his sixth goal of the season, after coming on as substitute, against
Blackburn Rovers in another 2–1 defeat. On 18 April 2015 Maguire scored the equaliser from the penalty spot in the 95th minute of the game against
AFC Bournemouth in a 2–2 draw. The following week on 25 April 2015, Maguire scored his eighth and final goal of 2014–15 against Yorkshire rivals
Leeds United, which was again from the penalty spot; Wednesday went on to lose the game 2–1.
Coventry City (loan) On 28 November 2013, Maguire signed on loan for
Coventry City until 5 January 2014. He made his Sky Blues debut on 30 November away to
Milton Keynes Dons, replacing
Carl Baker in the 65th minute. He scored two free-kicks in the 86th and 90th minutes to win the game for Coventry. Maguire was recalled by caretaker manager Stuart Gray for
Sheffield Wednesday's Boxing Day fixture against
Blackburn Rovers.
Rotherham United On 24 July 2015, Maguire signed a one-year contract with
Rotherham United. He made his debut in the first game of
the season on 8 August 2015 against
MK Dons at the
New York Stadium. In total, he made 14 league appearances (8 as a substitute) for Rotherham, plus one substitute appearance in the League Cup, but did not score during his spell at the club.
Oxford United (loan) On 26 November 2015, Maguire signed a two-month loan deal with
Oxford United. He made six League appearances, played in a notable victory over Premier League side
Swansea City in the third round of the FA Cup, and scored against
Yeovil Town in the area semi-finals of the Football League Trophy. Maguire scored 4 league goals in 2015–16, all during the final six games of the season culminating in Oxford's promotion to
League One. After prolonged negotiations he signed a further one-year deal in July 2016. He scored a career-best 17 goals for Oxford in
2016–17 but declined their offer of a new contract.
Sunderland On 22 June 2018, Maguire signed a two-year deal with
EFL League One side
Sunderland. On 24 August 2019, in his second season at the club, Maguire scored a hat-trick against
Wimbledon in a 3–1 home win. On 25 May 2021 it was announced that he would leave Sunderland at the end of the season, following the expiry of his contract.
Lincoln City On 7 July 2021, Maguire signed a two-year deal with
Lincoln City, joining Imps manager
Michael Appleton for a third time. Upon joining the club, he was given a number ten shirt ahead of the
new season. However, Maguire's debut was delayed for a month when he suffered a calf injury. Maguire would make his debut again
Cambridge United, on 11 September 2021, coming off the bench in a 5–1 victory. He scored his first goal for Lincoln City against
Carlisle United in the second round of the EFL Trophy, breaking the deadlock in the 45th minute, as the club lose on penalties (in which he missed) following a 1–1 draw. Maguire then scored his first league goal for Lincoln City, scoring from a penalty, in a 3–2 lost against
Milton Keynes Dons on 26 December 2021. Two weeks later on 11 January 2022, he scored a hat trick against his old club Sunderland, winning 3–1. In July 2022, Maguire was told by new Lincoln manager
Mark Kennedy that he was free to leave the club. On 22 August 2022, Maguire was charged by
The FA for breaching betting rules after Maguire was alleged to place 52 bets on football matches between March 2017 and February 2022. Maguire was subsequently suspended by Lincoln City. On 1 September 2022, Lincoln and Maguire parted ways by mutual consent.
Hartlepool United announced on 12 September 2022 that Maguire had signed for them. This signing was not completed, however, with their interim manager
Keith Curle saying in October that the deal had been placed on hold until there was an outcome to the case regarding his bets on football matches. Maguire and the club had agreed a contract which reflected the possibility of him being banned due to that case, but the
PFA rejected that change to the standard player contract.
Eastleigh On 24 July 2023, Maguire signed for
National League club
Eastleigh. He departed the club at the end of the
2024–25 season. ==International career==