"Barcelona will receive a percentage of the sale proceeds if the Senegalese defender is transferred to another club in the future," Barcelona wrote on their club website.
Mbacke Fall, 23, arrived at Barcelona in 2023 on loan from fellow MLS team Los Angeles FC.
A year later, Barcelona made Mbacke Fall's transfer permanent for a fee of around two million euros, according to Transfermarkt. He then joined Barça Atletic, or Barça B, Barcelona's official second team.
Throughout his career in Barcelona's youth team, Mbacke Fall played 59 times and scored four goals.
Meanwhile, St Louis City said the player, who previously played for Senegal's U17 national team, has a contract until June 30, 2028, for an undisclosed fee.
Mbacke Fall's contract has the option to be extended for two seasons, namely 2028/2029 and 2029/2030.
"Mamadou has the right attributes for us as we look to strengthen our defense. He's comfortable on the ball, reads the game well, and combines movement with defense. We believe his experience playing in the rigorous culture of MLS and European football will provide stability in the backline," said St. Louis City's Sporting Director Corey Wray.
Mamadou Mbacke Fall honed his football talents at the Montverde Academy in Florida before signing his first professional contract with MLS club Los Angeles FC (LAFC) in 2021.
He made his MLS debut at the age of 18, under coach Bob Bradley, and made 42 appearances there, scoring six goals in all competitions.
In 2022, Mamadou Mbacke Fall was loaned to Spanish La Liga club Villarreal. His league debut came in January 2023, when Villarreal defeated Girona 1-0.
Then, starting in September 2023, he was loaned out again to another Spanish League club, Barcelona, specifically Barcelona Athletic. The following year, Mbacke Fall was signed permanently by Barcelona before returning to MLS to play for St. Louis City starting in late January 2026.
