[3] Mário Sérgio joined Sporting CP on 25 June 2003 on a four-year contract, being the first signing of manager Fernando Santos; he said upon his arrival: "I am an ambitious player.

[6] Immediately after leaving the Lions, Mário Sérgio signed for two years with Associação Naval 1º de Maio also in the top division.

[17] On 17 August 2013, APOEL beat Apollon Limassol FC 1–0 to win the Cypriot Super Cup and Mário Sérgio scored a rare goal in the 35th minute.

[21] On 30 December 2016, after he cut ties with APOEL, free agent Mário Sérgio signed a six-month deal with Apollon Limassol with an option for a further season.

[24] Mário Sérgio played for the Portuguese under-21s for two years,[25] representing the nation at the 2004 UEFA European Championship, and was also in squad for the 2004 Summer Olympics football tournament.