Kaio Márcio Ferreira Costa de Almeida (born 19 October 1984) is a Brazilian swimmer who specializes in the butterfly.

He suffered from asthma attacks and began swimming for medical reasons, and under the influence of his father, José Márcio.

[10] In June 2004, participating in the second stage of the Circuit Mare Nostrum in Canet, France, Almeida broke the long-course South American record in the 200-meter butterfly with a time of 1:57.38, which was set by the Venezuelan Rafael Vidal since 1984 (1:57.51).

He finished fourth in the 4×100-meter medley,[15] breaking the South American record with a time of 3:33.02, along with César Cielo, Guilherme Guido and Eduardo Fischer.

[21] Almeida competed in the 2005 World Aquatics Championships in Montreal, where he was a finalist in the 100-meter butterfly, finishing in seventh place.

[29] Almeida won the gold medal in the 100-meter butterfly in the 2006 FINA World Swimming Championships (25 m) held in Shanghai.

[12][13] On 8 May 2009, at Maria Lenk Aquatic Center, Almeida swam the 200-meter butterfly in 1:53.92 seconds; the fifth-fastest time in the race's history and a South American record.

[44] In the Stockholm stage of the FINA World Cup in November 2009, Almeida broke his South American record in the heats of the 200-meter butterfly with a time of 1:51.46 seconds.

[50] At the 2010 FINA World Swimming Championships (25 m) in Dubai, Almeida won bronze in the 100-meter butterfly with a time of 50.33 seconds.

[52] Along with teammates César Cielo, Felipe França and Guilherme Guido, Almeida broke the South American record for the 4×100-meter medley with a time of 3:23.12 seconds, winning the bronze medal.

At the 2015 Pan American Games in Toronto, Ontario, Canada, Almeida won a gold medal in the 4×200-metre freestyle relay, by participating at heats.

[65] At the 2018 South American Swimming Championships in Trujillo, Peru, he won a silver medal in the 200 metre butterfly.