Birmingham City Reilly was born in
Warrington, Cheshire, and raised in
Solihull, West Midlands, He joined
Birmingham City's youth system at the age of seven, and began a two-year scholarship in July 2010. He was given a first-team
squad number in January 2012, and his first competitive involvement came when he was named among the substitutes for the third-round
FA Cup-tie against
Wolverhampton Wanderers, remaining unused. Reilly made his first-team debut on 28 January, coming on as an 80th-minute substitute for
Jordon Mutch in the fourth-round FA Cup-tie against
Sheffield United at
Bramall Lane, with Birmingham already 4–0 ahead. He signed his first professional contract, of one year, before the 2012–13 season, and was given a squad number before the visit to
Millwall in October. With
Hayden Mullins suspended and
Jonathan Spector injured for the visit of
Crystal Palace on 15 December, Reilly made his first start, and first appearance in
the Football League, alongside
Papa Bouba Diop in central midfield. He played the full 90 minutes as Birmingham came back from 2–0 down to draw. In first-half stoppage time of the visit to
Huddersfield Town in January 2013, "
Chris Burke's cross was headed into the path of Reilly, who smashed the ball into the net" from to score his first senior goal. He was substituted at half-time due to illness, and the match was drawn. In April, the club took up their option to extend Reilly's contract for another year. He ended the season with 18 league appearances, and signed a new two-year contract ahead of the 2013–14 campaign. Reilly had hoped to be a regular in the first team in the 2013–14 season, but an influx of new players, including midfielders
Andy Shinnie and
Tom Adeyemi, meant it took until late September and a good performance in the League Cup victory over Premier League club
Swansea City that he made his first league start, against
Reading. In the following game, a 4–0 win against
Millwall, manager
Lee Clark described the performance of Reilly and Adeyemi in partnership in defensive midfield as brilliant. They played regularly together until January, when new arrivals, including
Manchester City's
Emyr Huws and the experienced
Brian Howard, caused Reilly to fall out of favour. By the end of March, with Birmingham struggling, Reilly returned to the team, playing either in midfield or at left back. On the last day of the season, needing at least a draw at
Bolton Wanderers and for other results to go in their favour to avoid relegation to
League One, he started at left back, later moving into central midfield to replace the injured Huws, as the team came back from 2–0 down to equalise in the third minute of stoppage time and maintain their second-tier status. Eight minutes into his first match of the 2014–15 season, away at league leaders
Norwich City, Reilly scored the opening goal, a deflected effort from hit with his weaker right foot from , and in the next match, he made his 50th appearance. But in the face of competition from new signings
Stephen Gleeson and
David Davis, and later from loanee
Robert Tesche, he was unable to establish himself in the starting eleven. On 11 March 2015, he joined
League Two club
Burton Albion on loan until the end of the season. Birmingham manager
Gary Rowett intended the loan spell as an opportunity for the player to earn a new contract. Reilly made his Burton debut as a late substitute in a 3–0 win against
Accrington Stanley. He started the next match, but suffered a hamstring injury after 11 minutes that put an end to his season.
Burton Albion On 5 June 2015, Reilly agreed a two-year contract with Burton Albion, newly promoted to League One, subject to passing a medical. He scored his first goal for the club against
Bury in an
EFL Cup tie on 10 August 2016. He played regularly, making 20 appearances in all competitions and helping Coventry reach the
2017 EFL Trophy Final, but was unable to take part because of a hamstring injury suffered the previous day. Reilly was released by Burton when his contract expired.
Bury Ahead of the 2017–18 season, Reilly signed a two-year deal with another League One club,
Bury, where he was reunited with manager Lee Clark, who had given him his league debut for Birmingham. He was in the starting eleven for the opening fixture of the
2017–18 season, a 1–0 win at home to
Walsall, and made 15 league starts in the first half of the campaign as well as scoring his first goal for the club in an
EFL Trophy tie against
Stoke City U21s, after which he was loaned to League One club
Gillingham.
Gillingham Reilly was a regular in the starting eleven throughout his loan spell, He was released by mutual consent on 26 July 2019. He scored his first goal for Wimbledon in an
EFL Trophy tie against
Leyton Orient on 8 October 2019. He played in 35 of AFC Wimbledon's 41 matches before the season was ended early because of the
COVID-19 pandemic, mostly as a starter, and made a further 35 appearances in 2020–21 before his personal season was ended by an ankle fractured during a match against
Wigan Athletic in March. Reilly was released at the end of the season.
Leyton Orient Reilly signed for
Leyton Orient on a one-year contract on 31 August 2021. He made his league debut four days later as a substitute, and started in the EFL Trophy against
Southampton U21, He returned to the first-team squad in February 2022, but was then loaned to National League club
Solihull Moors, initially for a month. The deal was extended until the end of the season, and Reilly was a regular in the matchday squad but rarely started. He was released by Leyton Orient at the end of the season.
Banbury United Reilly signed for
National League North club
Banbury United on 16 September 2022, making twenty league appearances over the course of the season. During his first season, the club achieved a second consecutive promotion, being declared champions with two matches remaining. In May 2024, he departed the club. ==International career==