[8] On December 16, 2017, he set a career high for goals in a match by netting a hat trick against Valenciennes.

[11] On September 20, he made his European debut in the 2018–19 UEFA Europa League group stage for Rennes.

[14] After recording 15 goals and four assists across all competitions during the loan, Young Boys exercised the option to make the move permanent, effective July 1, 2021.

[15] On September 14, 2021, Pefok scored the winning goal in the opening match of the 2021–22 UEFA Champions League group stage.

His winner for Young Boys came in the final minute of stoppage time for a 2–1 win against Manchester United.

Pefok recorded a career-best 27 goals and five assists across all competitions during the year including UEFA Champions League and its qualifiers.

He also wore it on the back of his Young Boys jersey,[31][32] but decided to switch to using only his first name Jordan for Union Berlin.