[1] He played for Donegal in the Ulster Minor Football Championship, but his team did not win that competition.
[7][8] He was restricted to substitute appearances in the final four games, against Cavan, Tyrone, Monaghan and Mayo respectively.
[13] He also made a substitute appearance against Tyrone in the Ulster SFC semi-final, scoring 0–1; however, Donegal lost.
[14] In the 2017 All-Ireland Senior Football Championship Round 4A qualifier loss to Galway, Langan scored 0–1 during another substitute appearance.
[23] Langan started the 2018 Ulster Senior Football Championship preliminary round fixture against Cavan.
[41] Langan started the 2019 Ulster Senior Football Championship quarter-final against Fermanagh, the semi-final against Tyrone and the final against Cavan, and scored 0–1 in each of the three games.
[51] Against Monaghan in the next fixture, Langan started and scored five points in a ten-point victory for Donegal.
[56] Langan then started the 2020 Ulster Senior Football Championship victory against Tyrone, scoring 1–2.
[60] He then started the final, and scored Donegal's ninth point in the twentieth minute, in what proved to be the concluding game for his team that season.
[69][70] Langan started Donegal's opening fixture of the 2022 National Football League, against Mayo, and scored 0–4.
[80][81] He started the 2022 All-Ireland Senior Football Championship qualifier loss to Armagh, but was again held scoreless.
[82] Under the management of Bonner's successor Paddy Carr, Langan did not feature in the opening two fixtures of the 2023 National Football League, against Kerry and Tyrone respectively.
[89][90] Langan started the 2023 Ulster Senior Football Championship quarter-final against Down, but was held scoreless and went off injured following fifteen minutes of play, as his team lost the game.
[92] Langan featured in none of Donegal's three games against, respectively, Clare, Derry and Monaghan, in Group 4 of the 2023 All-Ireland Senior Football Championship.