Melvin Ajinca was born in Villeneuve-Saint-Georges, France and is the cousin of ex-NBA player Alexis Ajinca. In 2019-2021, Ajinca played basketball for Centre Federal Du Basketball. He played 17 games and averaged 5.5 points and 2.1 rebounds. He also played 4 games in the Belgrade League and averaged 8.5 points and 4.5 rebounds. In 2020-2021, he averaged 9.3 points and 3.9 rebounds in 19 games. In 2021-2022, he played in 3 different tiers for Centre Federal Du Basketball and played a total of 31 games. He finished the year with an overall average of 12.0 points and 3.9 rebounds a game.
Ajinca signed with Saint-Quentin Basket-Ball of the LNB Pro B in 2022. He averaged 8.4 points per game and was voted the best young player in Pro B. This past season he played in 35 games for Saint-Quentin and averaged 10.2 points per game.