In 2011 Harrison made his professional club debut for Sale Sharks.[2] He represented England U20 during the 2012 Six Nations Under 20s Championship and played in the last round as England defeated Ireland to win the tournament.[3] Later that year he was a member of the squad that finished seventh at the 2012 IRB Junior World Championship.[4]
Harrison played in the 2013 Anglo-Welsh Cup final which they lost against Harlequins to finish runners-up.[5] In June 2014 he was selected for the England squad to face the Barbarians.[6][7]
In January 2015 Harrison was called up to the England A squad.[8] Later that year he made his 100th appearance for Sale Sharks in a game against Harlequins on 6 November 2015.[9] In the summer of 2016 Harrison was a member of the England A squad that toured South Africa and played in both games as England defeated South Africa A to win the series.[10][11]
In May 2017 Harrison was invited to a training camp with the senior England squad by coach Eddie Jones.[12] The following month he played for England XV in a non-cap game against Barbarians.[13]
Harrison started for the Sale side that lost to La Rochelle in the semi-final of the 2018–19 European Rugby Challenge Cup.[14] At the end of that season he started for an England XV in their 51–43 victory over Barbarians.[15]
Harrison played in their 2021 Premiership play-off elimination against Exeter Chiefs.[16] He was a member of the Sale side that were league runners-up during the 2022–2023 campaign although did not play in the Premiership final defeat against Saracens.[17] In May 2025, Harrison announced he was leaving Sale after making over 300 appearances for the club during a fourteen year spell.[2]
