While at the Harlequins Academy Kerr was a part of England U17, U18 and U19 teams for 2022–2023, and toured South Africa for the U18 International Series in 2022.[5] Kerr played a total of five games for the U18s.[2] Kerr also played two games in 2023 for England U19s against Wales U19s and Italy U18s.[8][9]
Kerr was named in the England U20s squad ahead of the 2024 U20 Six Nations Championship.[10] He started against first round opponents Italy.[11] Kerr scored the first points of the match and scored seven points in total before being subbed off due to an ankle injury at half-time.[11] England won 11–36 in Treviso.[11] Missing the second round fixture against Wales, Kerr played the remainder of England's Six Nations campaign as starting inside centre and was named “player of the match” against their round three opponents, Scotland.[12] Kerr scored forty points overall for England,[13] including one try. England won the 2024 U20 Six Nations Championship, clinching the title by table point over Ireland.[14]
Following from his performances and status with England, Kerr was again in the England U20 squad for the 2024 U20 Championship in South Africa.[15] Aside from a pool stage fixture against Fiji U20, Kerr started and played every England U20 match, and proved vital in both knockout stage matches, scoring a combined thirty-two points (including one try) in the Semi-finals and Final. England won the 2024 U20 Championship, defeating France U20 21–13.[16][17]
In November 2024, he was called-up to the England A national rugby union team.[18] Kerr was selected for the England A squad again in November 2025.[19]
