In 2021–22, Terrier scored his first goal in the third match on 22 August, the only one of a Derby Breton win over Nantes at Roazhon Park. On 5 December, he scored his first hat-trick in a 5–0 win at Saint-Étienne. The season was the most prolific of his career with 21 goals, joint third in the league behind Kylian Mbappé and Wissam Ben Yedder and equal to Moussa Dembélé. He was the UNFP Player of the Month for March and made the Team of the Year.
