Mathias Lessort was born on September 29th, 1995 on the island of Martinique, a French territory in the Antilles. He grew up in the youth department of Chalon and joined the senior team in 2014. He moved to Nanterre and in 2017 was selected by Philadelphia in the second round of the NBA Draft. In the 2017/18 season he played for Crvena Zvezda, then spent time in Malaga from the Spanish league and and in 2019/20 the Frenchman played for Bayern Munich.
In 2020 Lessort moved to Cote d'Azur, Playing for Monaco in the EuroCup. In 23 games in the European competition, the big scored 12.5 points and grabbed more than 6 rebounds in 25 minutes on average. In the French league he played an average of 22 minutes per night, in which he scored 11 points and grabbed just under 6 rebounds.
In the two Eurocup final games (home and away), Lessort scored 25 points in 60 minutes and added 9 rebounds. Three of his record games last season in the EuroCup were against Unicaja Malaga, when in one game he scored 20 points, grabbed 9 rebounds and stole 4 balls, while in another game he scored 21 points and added 11 rebounds. Against Buducnost he provided 24 points and 7 boards.