Early life Nicolas was born to a Haitian father and an Algerian mother. Nicolas' early life had been full of abuse, poverty and violence. To atone for the rage he became prone to, he took up savate at the age of 14. He became multiple times French champion in different age categories. On 19 December 2021, He won the
FISav Savate world title against Anton Chernikov by unanimous decision. Following that victory Nicolas took the decision to transition to kickboxing rules, training out of Mahmoudi Gym.
Kickboxing transition On 22 June 2022, Nicolas faced Mohammad Amir from Iran at Kunlun Fight and Cicada FC 1 in Dubai. He won the fight by second round technical knockout due to low kicks. On 26 November 2022, Nicolas faced Ismael Ayaadi at Tour Event Fight 10. He won the fight by unanimous decision. Nicolas faced Abdellah Oussaid for the vacant MTGP K-1 World 77 kg title at Muay Thai Grand Prix on 23 March 2023. He won the fight by unanimous decision. Nicolas faced Ioannis Bitsios for the vacant ISKA World Super Middleweight K-1 Championship on 25 November 2023, at Tour Event Fight 11. He won the bout by knockout in the second round to win the vacant title.
ONE Championship Nicolas faced Magomed Magomedov at
ONE Friday Fights 47 on 12 January 2024. He won the bout by unanimous decision.
ONE Lightweight Kickboxing World Champion Nicolas faced defending
ONE Lightweight Kickboxing World Champion Regian Eersel on 6 April 2024, at the main event of
ONE Fight Night 21. He won the bout by unanimous decision to win the title. The rematch between Nicolas and Eersel for the
ONE Lightweight Kickboxing World Championship took place on 5 October 2024, at
ONE Fight Night 25.{{Cite web |last=Pico |first=Borna |date=2024-08-06 |title=Regian Eersel Versus Alexis Nicolas Rematch Official For October 5 The trilogy bout between Nicolas and Eersel took place on 5 April 2025, at
ONE Fight Night 30.{{Cite web |last=Pico |first=Borna |date=2025-03-11 |title=Trilogy Title Bout Between Regian Eersel and Alexis Nicolas Set for ONE Fight Night 30 on April 4 On September 9, 2025, it was announced that Nicolas was released from ONE Championship. ==Mixed martial art career==