2014 Short Course World Championships (Doha, Qatar)
Mignon was a key relay piece for France in Doha, helping his country to 3 medals in the 4×100 free (gold), 4×50 medley (silver) and 4×100 medley (bronze).
2015 World Championships (Kazan, Russia)
In Kazan, Mignon swam on the prelims of the 4×100 free relay, registering an anchor split of 48.79. The relay went onto win gold, earning Mignon his first long course world champs medal.
2016 Olympic Games (Rio de Janeiro, Brazil)
Mignon swam on the prelims relay of France’s 4×100 free relay, splitting 48.59 on the lead off leg. The relay went on to finish 2nd, netting Mignon his first Olympic medal, a silver.
2019 World Championships (Gwangju, Korea)
Mignon swam the leadoff leg of France’s third place mixed 4×100 free relay team (3:22.11) ahead of Mehdy Metella, Charlotte Bonnet and Marie Wattel. He also was part of France’s eighth place 4×100 free relay team (3:13.34) with Jeremy Stravius, Tom Paco Pedroni, Mehdy Metella.
He also finished seventh in the 100 free (48.43).