[4] On 14 December, he made his first team debut, coming on as a substitute for Bernardo Silva in the extra time of a 1–0 league victory against Marseille.

[15][16] On 3 August 2019, Diallo made his debut for Paris Saint-Germain in the Trophée des Champions, which ended as a 2–1 win for PSG over Rennes.

[20] On 1 September 2022, Diallo completed a return to Germany, signing for Bundesliga club RB Leipzig on a season-long loan with an option-to-buy for a reported fee of €25 million.

[21][22] On 15 August 2023, Diallo signed for Qatar Stars League club Al-Arabi for a transfer fee in the region of €15 million.

[26] He was part of Senegal's squad for the 2021 Africa Cup of Nations; the Lions of Teranga went on to win the tournament for the first time in their history.

[29] Diallo played in all four of Senegal's matches at the 2022 FIFA World Cup as the nation reached the round of 16 for the first time since its debut in 2002.

[3] Michael Zorc, the sporting director of Borussia Dortmund, described Diallo as "a modern, strong central defender who is very intelligent.

[33] Monaco Paris Saint-Germain RB Leipzig Senegal Individual Media related to Abdou Diallo at Wikimedia Commons