Ryerson signed for Viking from Lyngdal IL in the summer of 2013.[2] He got his breakthrough for the first-team in the 2016 season, when he played 18 matches in the league. Ryerson played primarily right-back in those matches.
On 17 January 2023, Borussia Dortmund signed Ryerson to replace the injured Thomas Meunier, with a contract until June 2026.[6] One week later, on 25 January, he scored his first goal in a 2–1 away victory over Mainz.[7] In the following month, he made his Champions League debut on 15 February in a 1–0 victory over Chelsea in the round of 16 first leg.[8] On 30 March 2024, he scored the second goal in a 2–0 away win over Bayern Munich, to be his club's first victory in Der Klassiker since 2019 and the first win at Allianz Arena in 10 years.[9]
Ryerson's father was born in the United States, and his mother was born in Norway.[citation needed] His cousin is Norwegian football player Mathias Rasmussen.[12]