He rose to prominence at Fluminense, where he made 165 appearances across three years, and was named in the Bola de Prata and Prêmio Craque do Brasileirão teams when they won the Campeonato Brasileiro Série A in 2010.

Les Girondins won the cup final on 31 May, with Mariano playing the full 90 minutes of the 3–2 victory against Évian Thonon Gaillard and receiving the first yellow card for a foul on Daniel Wass.

[11] He made his debut on 11 August in the UEFA Super Cup, coming on in the 80th minute for Kévin Gameiro in a 5–4 extra-time loss to fellow Spaniards Barcelona in Tbilisi.

[16] He made 26 total appearances as his club won the title in his first season, and scored twice including a 20-metre strike to open a 2–0 win over İstanbul Başakşehir at the Türk Telekom Stadium on 15 April 2018.

[17] On 29 July 2020, Mariano joined Atlético Mineiro on a free transfer, returning to the club twelve years after his first spell and reuniting with his former coach at Sevilla Jorge Sampaoli.

[1] In September 2010, amidst good form for Fluminense, Mariano was called up for the first time to the Brazil national team by coach Mano Menezes, for friendlies the following month.