In 2017, at just 13 years old, he joined Real Madrid's youth team.
Ndiaye quickly made a name for himself within the white team, helping them secure the 2018 Minicopa.
During the summer of 2020, he obtained Spanish citizenship through naturalization.
In the 2020–21 season, Ndiaye was a key player on the junior team and participated in the 2021, where he earned several MVP awards. He also contributed to Real Madrid's victory in the Spanish Super Cup.
Ndiaye made his debut in the EuroLeague in September 2021 with Real Madrid, playing against Fenerbahce. His opportunity arose when Edy Tavares took paternity leave. He became the seventeenth young player to make his debut under the guidance of coach Pablo Laso.[2]
During the 2022–23 season, he became a regular member of Real Madrid's first team in the Liga ACB.[3]