The former World Cup-winning defender claimed the Real Madrid superstar can be “too selfish” and suggested other players may be better suited to lead Les Bleus.
Leboeuf specifically highlighted William Saliba and N'Golo Kante as players who possess stronger captaincy credentials ahead of the tournament in North America.
"No, Kylian Mbappe is not a leader for me because he's too selfish in his thoughts, in the way he thinks," Leboeuf told SportsBoom, on behalf of CSB.
"I don't know him. I met him only once when he was with the national team, and he was playing for Paris Saint-Germain, having just signed for Paris Saint-Germain at the time.
“Again, he's a great lad, well-educated, but his thinking, his way of thinking about football, doesn't align with my values of the game.”
"That's why I like people like William Saliba and N’Golo Kante, players like that who are ready to sacrifice for the team," he continued.
"That's the difference for me, and that's what counts for me the most. Antoine Griezmann, as well, was a real leader in terms of the way he was playing and the way he was thinking about football.
“ I liked Ousmane Dembélé's comment, saying that if I don't track back, the coach won't put me in, and that's the reality of football. Mbappé is a superstar, but he's not the best teammate in the world; that's my problem."