Ilionis Guillaume gained her first international experience at the U18 World Championships in Cali in 2015 , where she finished fourth in both the hurdles and triple jump. In 2016 she qualified for the U20 World Championships in Bydgoszcz, Poland , where she finished ninth in the triple jump. In 2017 she won the silver medal triple jump at the U20 European Championships with a wind-assisted 13.97 m.
Personal best
100 m hurdles: 13.23 s (−0.1 m / s), June 3, 2017 in Marseille
60 m hurdles (hall): 8.28 s, March 4, 2017 in Haale
Long jump: 6.14 m (+1.4 m / s), October 10, 2015 in Salon-de-Provence