Olympiacos swimming club is the swimming department of the major Greek multi-sport club, Olympiacos CFP, based in Piraeus, Greece. The department was founded in 1925, being one of the founding members of the Hellenic Swimming Federation.

Olympiacos is the most successful team in the history of Greek swimming, having won a record 64 Greek League Championships, 9 Greek Open Water Championships, 4 Greek Cups (25m pool), 1 Panhellenic Masters Championship and 1 Greek Super Cup. The club's dominating success can be further evidenced by the fact that all other Greek swimming clubs have won a combined total of 34 Greek League titles. Olympiacos also hold the record for the most consecutive Greek League titles won, with twenty-eight (28) in a row (1996–2023), which is a record in Greek sports history. Olympiakos swimming department holds the world record of having won at least one title in every season, for fifty-three (54) consecutive years. Since 1997, the department is led by head coach Nikos Gemelos, who has coached Olympiacos to 27 consecutive Greek League titles.

Olympiacos has produced some of the greatest swimmers in Greek swimming history, such as the Olympic silver medalist, five-time Olympian, two-time World Champion, World Cup gold medalist, and two-time European Champion^[1] Spyros Gianniotis, who is considered the greatest Greek swimmer of all time.^[2][3]

• Olympiacos CFP