Julian Ryerson was born on 17 November 1997 in Lyngdal, Norway, to a Norwegian mother and an American father. His cousin is fellow Norwegian footballer Mathias Rasmussen. He started professionally with Viking FK in the Norwegian Eliteserien, breaking into the first team in 2016.
In July 2018 he joined 1. FC Union Berlin in the 2. Bundesliga. He helped Union earn promotion to the Bundesliga and reach European competition, scoring crucial goals including a 1-0 away win over Maccabi Haifa in the 2021-22 Conference League.
On 17 January 2023 Borussia Dortmund signed him to cover for the injured Thomas Meunier. He has since become a regular starter, scoring the second goal in a 2-0 away win over Bayern Munich in March 2024 — Dortmund's first Klassiker victory since 2019 and first away win at the Allianz Arena in a decade. In February 2026 he provided four assists, all from crosses, in a 4-0 win over Mainz, becoming only the fourth Bundesliga player ever (and second Dortmund player) to do so.
For Norway he made his senior debut on 18 November 2020 in a UEFA Nations League match against Austria and has earned around 40 caps with one international goal.
Standing 1.83 m, Ryerson is a right-back / right wing-back who can also play on the left, and combines stamina, dribbling and crossing — a no-frills, full-throttle modern fullback profile.