Fournier helped France to EuroBasket victory in 2013 in his first senior campaign and then to World Cup bronze in 2014, having already tasted success with his country's junior teams, winning the bronze medal at the 2011 U20 European Championship in Spain and silver at the U18 in 2009. On both occasions, he was included in the All Tournament Team. He was drafted (26th overall) and signed for the Denver Nuggets and was then traded to Orlando in June 2014. Previously, the product of the INSEP academy turned professional with Nanterre in Pro B before switching to Poitiers. At age 19, he became the youngest player in French League history to score at least 20 points in a game. He was twice awarded the league's Most Improved Player honour and its Rising Star prize (2011, 2012). His father Francois and mother Meriem were competitive judo fighters.