Olympiacos was founded on March 10, 1925, in the port of Piraeus, when the members of Peiraikos Podosfairikos Omilos (Sport and Football Club of Piraeus) decided, during a historical assembly, to dissolve the two clubs in order to establish a unified new one, with an emblem depicting the profile of an Ancient Olympic Games winner.
The Andrianopoulos brothers, however, were those who significantly raised the reputation of the club and added glory to it.
Olympiacos immediately caught the attention of locals, back then their fanbase consisted mainly of the working class, with the team filling the Piraeus Velodrome, present day Karaiskakis Stadium and becoming EPSP Champions (Enosi Podosferikon Somation Pireos – Regional Championship in Peiraias) the seasons 1925,1926,1927[1] In 1926, the Hellenic Football Federation was founded and organized the Panhellenic Championship, the 1927–1928 season, the first national championship, were the regional champions from EPSA league (Athens), EPSP league (Peiraias) and EPSM league (Thessaloniki) compete for the national title through play-offs with Aris FC becoming the first champion.
During that season they played friendly games with each other and together formed a group called P.O.K.The second Panhellenic Championship took place in 1929–30 and the 3rd found Olympiacos winning the Greek national league title, the 1930–31 season, for the first time in his history.
Since that time the club's first team has competed in numerous nationally and internationally organised competitions.