Founded in 1946, it currently competes in the Campeonato de Portugal, holding home games at Campo Engenheiro Carlos Salema, with an 8,500 capacity.

In January 1936, Rui de Seixas, then-president of Chelas Football Club, first raised the idea of creating a single club that represents the entire eastern part of the city of Lisbon, but he was heavily criticized for it, causing him to give up the idea almost immediately.

[1] In April 1946, at a coffee shop, the idea of a merger is first brought up by José Marques de Oliveira, then vice-president of Chelas FC, to journalist Arthur Ines.

[2] In the 1949–50 season, Oriental won the league title in the Segunda Divisão and achieved direct promotion to the highest division of Portuguese football.

= Position; Pl = Match played; W = Win; D = Draw; L = Lost; GS = Goal scored; GA = Goal against; P = Points Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.