[3] Fagerson enrolled in the BT Sport Scottish Rugby Academy in 2015-16 as a Stage 2 player.

[7] Fagerson made his Pro12 debut for the Warriors against Ulster on 23 September 2016 when he replaced Ryan Wilson.

[12] Fagerson gained his first senior cap for Scotland on 16 June 2018 when playing against the United States.

[14] In 2023 Fagerson, and his brother, were selected in Scotland's 33 player squad for the 2023 Rugby World Cup in France.

[15] He is the younger brother of Scotland international rugby union player Zander Fagerson.