The 17-year-old attacker has been under contract with Borussia Dortmund since January 2023. He previously played for RSC Anderlecht in Belgium and has made one appearance for BVB as of June 2023 (all figures are accurate as of that date).

"We are very pleased that Julien and his family are putting great trust in us. Julien is a fast, technically strong and creative winger in whom we see great potential," said BVB sporting director Sebastian Kehl in late-January 2023, adding: "We want to work together to unlock that potential and drive forward his development, as we have demonstrated several times with talented youngsters in the past. Our main focus is to integrate Julien into our first team squad and the new environment as quickly as possible and to bring Julien up to the level of the Bundesliga step by step."

The youngster had already played six games in the Jupiler Pro League for the 34-time Belgian champions, RSC Anderlecht. Just 17 days after his 16th birthday, he played for Anderlecht in the Belgian top tier, and even scored his first goal in just his second game, finding the top left corner from the edge of the box. A fast striker with a penchant for skills, he even earned himself the nickname "L’Éclair" – lightning – back home in Belgium. A number of clubs were interested in him, but BVB won the race to secure his signature. On Matchday 34 of the 2022/23 season, he made his Bundesliga debut, coming on as a substitute in the home game against Mainz. In the club's history, only Youssoufa Moukoko and Nuri Sahin have made their first appearances for BVB at a younger age.

Julien Duranville first came into contact with Borussia Dortmund some eight years earlier, in autumn 2014, when a BVB side including Mats Hummels and Sebastian Kehl travelled to RSC Anderlecht for a Champions League match, and Julien Duranville was … a ballboy! Since then, Belgium's most talented young footballer has kept an eye on BVB, watching with interest as highly rated youngsters such as Ousmane Dembélé and Jadon Sancho took the last big step in their sporting development in Dortmund. That emboldened him to follow in their footsteps and join the Black and Yellows.

"I think it's fantastic how young players are developed here. I was a fan of Ousmane Dembélé as a young boy. I love the way he plays football, and at the time, I was desperate to find out which club was behind it. That was the first time that I really became aware of BVB. And then came Jadon Sancho. A great footballer, and – like Dembélé and I – he's at his best on the wing," he told the Borussia members' magazine (April 2023 issue). The first few weeks at BVB were challenging. As his father had to take care of Julien's two younger siblings, who were still in school in his old home country, Julien and his mother initially moved into a hotel room.