Pure product of the Monaco Academy, Diallo made his professional debut with the club from the Principality and quickly added Champion of France to his CV. But after a brief experience in Belgium, it was on the other side of the Rhine that the defender made his name.
With Mainz, in the first instance (2017-2018), then with Dortmund a year later (2018-2019), Diallo made his name thanks to his versatility and professionalism. Attributes that allowed him to become a key figure in all of the France youth teams before signing for Paris Saint-Germain in summer 2019.
