When Maguire retired from playing he initially left the game and taught
physical education before signing as a strength and conditioning coach for Canberra. He later became an
assistant coach for the Raiders' reserve grade under
Mal Meninga. Maguire was eventually promoted to assistant coach of the Canberra first team alongside
Matthew Elliott, before leaving the club in 2004 to take the assistant coaching job at
Melbourne Storm under a former Raiders teammate,
Craig Bellamy. Maguire was an integral part in Melbourne's stripped NRL premierships and took control of first team affairs when head coach Bellamy took up representative duties for the Blues in
State of Origin. This earned him plaudits from senior coaches in the NRL and Maguire was linked with a move to
Brisbane Broncos as head coach in 2008. He was heavily linked with a move to English club
Wigan Warriors towards the end of the 2009 season and signed a three-year deal with the
Super League side on 7 October 2009.
Wigan Warriors Maguire started his Wigan coaching career with a victory against the
Crusaders in his first home match of the season. He ended the Halliwell Jones hoodoo (Wigan hadn't won a competitive game away at Wire since they last played at Wilderspool) against
Warrington in a thrilling match which Wigan won 22–20. He won
RLW coach of the month for February. Maguire then recorded his biggest victory as a Wigan coach, beating nearest rivals
St. Helens in the last ever
Good Friday derby match at
Knowsley Road. He and his assistant
Shaun Wane helped guide Wigan to the
League Leaders' Shield in 2010. This was the first time Wigan topped the table in 10 years and marked a trophy winning start to "Madge's" Wigan coaching tenure. Maguire guided Wigan to their first
Super League Grand Final appearance in seven years as the Wigan club beat
Leeds in a semi-final at Headingley by a scoreline of 26–6 on 25 September 2010. Maguire was crowned Coach of the Year 2010 at the annual Super League 'Man of Steel' awards dinner. Maguire managed the Wigan side to their first Super League Grand Final win in over 10 years beating their arch rivals in the
2010 Super League Grand Final victory over
St. Helens at
Old Trafford. The following February his Wigan side took on
2010 NRL premiers
St. George Illawarra Dragons in the
2011 World Club Challenge but were defeated. In 2011 Maguire announced his resignation from Wigan, in order to replace the retiring
John Lang as head coach of
National Rugby League club the
South Sydney Rabbitohs for the
2012 NRL season. Maguire coached Wigan to the
2011 Challenge Cup Final victory over the
Leeds Rhinos at
Wembley Stadium.
South Sydney Rabbitohs Maguire joined the
South Sydney Rabbitohs in October 2011, after the end of the
NRL and Super League seasons. He had signed a contract with the club earlier in the year, to replace the retiring John Lang. The Rabbitohs performed well during the
2012 NRL season with Maguire credited for the successful move of
Greg Inglis from centre to
full-back. The team progressed to within one game of the
2012 NRL Grand Final. The following year, Maguire guided Souths to within one game of the
2013 NRL Grand Final but the club were defeated 30–20 by
Manly-Warringah in the preliminary final. In the
2014 NRL season, Souths were tipped to be winners of the minor premiership, along with the
Sydney Roosters and
Manly-Warringah Sea Eagles. The first finals round saw Souths defeat Manly, then facing the Roosters in the preliminary final. Unlike the last round of the ordinary season, Souths overcome an early 12–0 deficit to score 32 unanswered points, eventually winning the match 32–22. Under Maguire's coaching this was the first time since 1971 that South Sydney had reached a grand final. Souths defeated the
Canterbury-Bankstown Bulldogs 30–6 in the
2014 NRL Grand Final, securing their 21st premiership and their first since
1971. In September 2017, Maguire was terminated as coach of South Sydney despite having two years remaining on his contract.
Wests Tigers On 28 October 2018, Maguire was announced as Head coach of
Wests Tigers for the next three years. In his first year in charge of the
Wests Tigers, Maguire guided the club to a ninth-place finish narrowly missing out on the finals. In round 4 of the
2020 NRL season, Wests lost 28–23 to the struggling Gold Coast side giving them their first win in 364 days. In the post match press conference, Maguire spoke to the media saying “I'm sick and tired of the ups and downs of the performances. We need to change that. That's what this club has been, I didn't want to say that, but it's the truth. and the truth is we need to fix how we do things when we are performing". During the half-time interval in round 12 of the
2020 NRL season, Maguire was seen on a dressing room camera berating his players for their poor first half performance against the
New Zealand Warriors. Maguire was then seen kicking a chair across the room. At the end of his second year in charge of the
Wests Tigers, the club finished a disappointing 11th on the table and missed out on the finals. Wests were also one of only five teams to concede over 500 points in the
2020 NRL season. In the
2021 NRL season, Maguire guided the
Wests Tigers to a disappointing 13th placed finish on the table including a 38–0 loss against
Wooden Spoon side Canterbury in the last round. After the season had concluded, Maguire's position as head coach came under intense scrutiny but on 21 September 2021, the
Wests Tigers board declared that Maguire would continue as head coach in 2022. On 6 June 2022, Wests Tigers announced Maguire had been terminated as head coach with the club sitting 13th on the table. He was replaced by interim coach
Brett Kimmorley.
New Zealand In 2018, Maguire became head coach of the New Zealand national rugby league team. Maguire took New Zealand to the semi-final of the
2021 Rugby League World Cup where they lost against Australia. On 4 November 2023, Maguire coached New Zealand to the Pacific Championships trophy upsetting Australia 30–0 in the final. New Zealand had won just one game against the Kangaroos in the previous nine outings, with a run of three-straight losses including an 18-point drubbing just a week earlier. In December 2023, Maguire signed a contract to become New South Wales head coach starting in 2024. It was reported that Maguire had been given an ultimatum by the New Zealand rugby league board to either stay solely with them or his contract would be terminated.
New South Wales In November 2023, Maguire was appointed coach of New South Wales. There was much optimism heading into the first match of the series but this changed when
Joseph Sua'ali'i was sent off in the 8th minute for a high tackle on
Reece Walsh. New South Wales lost 38–10, recording their biggest defeat in Sydney. In the aftermath, some of Maguire's decisions came under fire, particularly his decision to limit play time of captain
Jake Trbojevic. New South Wales would go on to win game two of the series in emphatic fashion defeating Queensland 38–18 at the Melbourne Cricket Ground, leading 34–0 at half time in a dominant display. In game three, Maguire guided New South Wales to a 14–4 victory over Queensland to win the series. It was the first time since 2005 that a New South Wales team had won a deciding game in Brisbane and Maguire was praised for his tactics, leading to immediate speculation he would return to full-time NRL coaching if given the opportunity.
Brisbane Broncos On 1 October 2024, Maguire was appointed coach of the Brisbane Broncos. on a three year contract ending in 2027. The Brisbane club finished first in the
2025 NRL Pre-season Challenge played in February, prior to the commencement of the regular
2025 NRL season in March. At the end of the
2025 NRL season, the Brisbane side secured fourth place on the ladder after defeating the
Melbourne 30–14 in Round 27 at
Suncorp Stadium. Maguire completed one of the great rugby league coaching journeys when he led the Brisbane Broncos to a dramatic 26–22 victory over Melbourne in the
2025 NRL Grand Final, ending the club’s 19-year premiership drought. loss in February 2026 On 19 February 2026, he coached Brisbane in their
World Club Challenge loss against
Hull Kingston Rovers. ==Honours==