2006–2008 Oliveira swam at the
2006 Pan Pacific Swimming Championships, where he finished 6th in the 4 × 200-metre freestyle, 14th in the 100-metre freestyle, 25th in the 200-metre freestyle, and was disqualified in the 4 × 100-metre freestyle. His first appearance in World Championships, was at the
2007 World Aquatics Championships held in
Melbourne, where he helped the 4 × 100-metre and 4 × 200-metre freestyle relay teams to qualify for the
2008 Summer Olympics. Oliveira earned 46th place in the 50-metre freestyle, 26th in the 100-metre freestyle, 17th in 200-metre freestyle, 8th in the 4 × 100-metre freestyle, and 11th in the 4 × 200-metre freestyle. At the
2007 Pan American Games, Oliveira won the gold medal in the 4 × 100-metre freestyle relay and in the 4 × 200-metre freestyle. He also ranked fourth in the 200-metre freestyle.
2008 Summer Olympics At the
2008 Summer Olympics in
Beijing, he participated in the 4 × 100-metre freestyle relay (where he was disqualified), 4 × 200-metre freestyle (16th place), and 4 × 100-metre medley (14th place). with
Thiago Pereira,
Rodrigo Castro, and
Lucas Salatta, he got the 10th place in the 4 × 200-metre freestyle. He also competed in the 100-metre freestyle finals, placing 8th, and finished in 18th place in the 200-metre freestyle. He competed in the
2010 Pan Pacific Swimming Championships in
Irvine, where he finished 5th in the 4 × 200-metre freestyle, 12th in the 100-metre freestyle, and 22nd in the 200-metre freestyle. At the
2010 FINA World Swimming Championships (25 m) held in
Dubai, the Brazilian national team, composed of
César Cielo,
Nicholas Santos,
Marcelo Chierighini, and Nicolas Oliveira, won the bronze medal in the 4 × 100-metre freestyle, with a time of 3:05.74 (South American record), with Brazil beating the American team. He also won the bronze medal in the 4 × 100-metre medley race, by participating at heats. Participating in the
2011 World Aquatics Championships held in
Shanghai, Oliviera finished 13th in the 200-metre freestyle, 9th in the 4 × 100-metre freestyle, and 14th in the 4 × 200-metre freestyle. He was in
2011 Summer Universiade, where he won the silver medal in the 4 × 100-metre freestyle. At the
2011 Pan American Games in
Guadalajara, Oliviera won the gold medal in the 4 × 100-metre freestyle relay and silver in the 4 × 200-metre freestyle. He also came in ninth place in the 200-metre freestyle.
2012 Summer Olympics At the
2012 Summer Olympics in
London, Oliveira finished 9th in the 4 × 100-metre freestyle and 24th in the 100-metre freestyle. At the
2013 World Aquatics Championships in
Barcelona, he finished seventh in the
4 ×100-metre freestyle, along with
Fernando Santos,
Marcelo Chierighini, and
Vinícius Waked. In the
200-metre freestyle, Oliveira classified to the semifinals with the best time of his life without super suits, 1:46.99. He also finished 11th in the
4 × 200-metre freestyle, along with
João de Lucca,
Fernando Santos, and
Vinícius Waked. At the
2014 Pan Pacific Swimming Championships in
Gold Coast, Queensland, Australia, Oliveira won a bronze medal in the Brazilian 4 × 100-metre freestyle relay, along with
João de Lucca,
Marcelo Chierighini, and
Bruno Fratus. He also finished 5th in the 100-metre freestyle, 6th in the 200-metre freestyle, and 17th in the 50-metre freestyle. At the
2015 Pan American Games in
Toronto, Canada, Oliveira won a gold medal in the 4×200-metre freestyle relay, where he broke the Pan Am Games record with a time of 7:11.15, along with
Luiz Altamir Melo,
Thiago Pereira and
João de Lucca, and finished 5th in the 200-metre freestyle. He also won a gold medal in the 4×100-metre freestyle relay, by participating at heats. At the
2015 World Aquatics Championships in
Kazan, he finished 15th in the
Men's 4 × 200 metre freestyle relay, along with
João de Lucca,
Thiago Pereira and
Luiz Altamir Melo., and 22nd in the
Men's 200 metre freestyle.
2016 Summer Olympics Oliveira competed for the last time at the
2016 Summer Olympics, where he went to the
Men's 4 × 100 metre freestyle relay final, finishing in 5th place. He also competed in the
Men's 4 × 200 metre freestyle relay, where the Brazilian relay finished in 15th place, and in the
Men's 100 metre freestyle, finishing 28th. At 29 years old, he said goodbye to swimming after three Olympic Games (Beijing 2008, London 2012 and Rio 2016), and six World Championships (Melbourne 2007, Rome 2009, Dubai 2010, Shanghai 2011, Barcelona 2013 and Kazan 2015). ==Records==