Jullien joined Warrington Wolves ahead of the 2016 Super League season, making his Super League debut from the bench in the round one victory over the Leeds Rhinos. He scored his first Super League try in a victory over the Wigan Warriors on April 28.[4]
Jullien was a member of the France squad for the 2014 European Cup, but did not feature. He made his France début the following year in a victory over Serbia. He also participated for France in the 2015 European Cup where he played all 3 matches as well as in a test matchArchived 2015-10-26 at the Wayback Machine against England. The following year he made another appearance for France in their end of year test match against England in Avignon. In the 2017 World Cup he played in all three games for France.[6]
In the opening game of the 2021 Rugby League World Cup group stage, Jullien scored two tries for France in a 34-12 victory over Greece.[7]