Born in Les Ulis, Essonne, to Malian parents, Marega began his career at Évry FC, before moving to Vendée Poiré-sur-Vie Football of the Championnat National in 2012, and fellow league team Amiens a year later.

[6] He made 13 appearances in his first campaign at the Estádio do Dragão – mostly as a substitute – and scored once in a 2–0 home win over Gil Vicente in the Taça da Liga on 2 March.

[18] On 16 February 2020, after scoring the winning goal on his return to Vitória, Marega gave the middle finger to the home fans who had been racially abusing him.

[22] On 10 May 2021, Saudi Arabian club Al-Hilal announced the signing of Marega on a three-year contract as a free transfer, with a salary of €5 million per year.

[23] He won the AFC Champions League in his first year, with a goal in the semi-final 2–1 win at compatriots Al Nassr,[24] followed by one in the 2–0 final victory over South Korea's Pohang Steelers.

[25] At the 2022 FIFA Club World Cup, held the following February in Morocco, Marega scored in the final, a 5–3 loss to Real Madrid.

[28] Marega made his debut for the Mali national team on 25 March 2015, in a friendly against Gabon in Beauvais, France; he started in the 4–3 defeat.

On 4 September 2016, he scored his first international goal in a 2017 Africa Cup of Nations qualification game against Benin, helping towards a 5–2 win at the Stade du 26 Mars.

[36] His older brother Houssein Marega, played active football in France for FC Versailles 78 , SO Romorantin, Sainte-Geneviève Sports , as well as Scottish club Queen of the South.