[1] He was drawn to the sport after watching a National Football League game on television with his cousin and had his first practice with the Caïmans three days later.

[4] In 2016, he arrived in Canada, playing one season of collegiate football for the McGill Redmen before a sudden increase in international student tuition forced him to return to France.

[9] The following month, in April, he was selected by the Hamilton Tiger-Cats as the first overall pick in the inaugural European CFL draft, part of commissioner Randy Ambrosie's initiative to grow the league's presence internationally.

[10][11] He began the season as a member of the practice squad,[12] but made his debut during their week 9 matchup against the BC Lions on August 10, recovering an onside kick that led to a second-quarter field goal in the 35-34 victory.

After a successful tryout at age 16, Gnahoua was selected to the France national under-19 team and subsequently played at the 2012 IFAF U-19 World Championship in Austin, Texas.

Gnahoua made his debut for the senior national team in 2014, helping France win a bronze medal at the European Championship held in Austria.