Restencourt began the 1998–99 season on the Junior Grand Prix (JGP) series, winning gold in Saint-Gervais-les-Bains, France and then in Chemnitz, Germany. In November 1998, he competed at the 1999 World Junior Championships in Zagreb, Croatia. Ranked third in his qualifying group, first in the short program, and second in the free skate, he was awarded the silver medal behind Russia's Ilia Klimkin. In January 1999, he finished 8th at his first senior ISU Championship, the European Championships in Prague, Czech Republic. In March, he won gold at the JGP Final.