She representied Europe at the 2016 Junior Ryder Cup and was on the winning Vagliano Trophy team in 2019.

[2] Roussin won the Spanish International Stroke Play and St Rule Trophy in 2016, and the Grand Prix de Valcros in 2017.

She played in the Ladies European Tour event Jabra Ladies Open and was one stroke clear of the field heading into the final round,[3] finishing runner-up as England's Annabel Dimmock won by one shot.

Roussin reached number 1 in the World Amateur Golf Ranking in January 2020.

[5] Roussin turned professional in August 2021 and claimed a victory in just her second event as a professional, the Skaftö Open on the Ladies European Tour, two weeks after she ended life as an amateur, where she shot a second round of 60 (−9).