Todibo, 19, has represented France at U-20 level and is widely considered as one of the brightest defensive prospects in European football.
The towering Toulouse defender was said to be attracting interest from a host of Premier League club's but the Blaugrana have since won the race for his services.
Primarily used in defence with the Ligue 1 side, Todibo has been touted as a long-term replacement for Gerrard Pique as a powerful ball-playing centre-back.
"FC Barcelona have reached an agreement with the French player Jean-Clair Todibo for him to join the Club from 1 July 2019," read a statement on the club's official website. "The player's contract with Toulouse FC ends on 30 June this year and so he will join on a free transfer."
"Todibo is a tall, right-footed defender who can play at centre back and also in the centre of the midfield. At the youth level he often featured in the middle of the field given his ability on the ball.
"One of his best qualities is his physical presence and his ability in the air. At just 19 years of age, the young talent comes to FC Barcelona as one of the most promising players in European Football in his position."