On 25 July 2022, Leonard signed for EFL League Two club Northampton Town on loan for the duration of the 2022–23 season.[6] His first professional goal, a precise finish from the edge of the box, opened the scoring in a 2–2 draw at home to Sutton United on 25 October.[7] Leonard played 45 matches in the league, including the 1–0 away win over Tranmere Rovers on the last day of the season that sealed third place and promotion to League One.[8][9]
On 29 July 2023, Leonard re-joined Northampton Town for a second season on loan.[10] He was named in the starting eleven for all 46 league games, was pivotal in securing a successful first season back in League One for the club, and won both the fans' Player of the Season and players' Player of the Season awards.[11][12]
Birmingham City
On 25 July 2024, recently relegated League One club Birmingham City signed Leonard on a four-year contract. The fee was undisclosed.[13] He made his debut in the starting eleven for the opening fixture of the season, a 1–1 draw at home to Reading.[14]