[4] An academy graduate of Paris Saint-Germain (PSG), Nianzou made his professional debut on 7 December 2019 in a 3–1 league win against Montpellier.

[9] On 11 March, Nianzou played his final match for PSG, a 2–0 UEFA Champions League victory over Borussia Dortmund.

He left the Parisian club upon the expiration of his contract, and signed for Bayern Munich on a free transfer.

[10] On 1 July 2020, Bundesliga club Bayern Munich announced the signing of Nianzou on a four-year deal.

[citation needed] He was an important part of the French team which finished third at the 2019 FIFA U-17 World Cup.