Okimoto competed in the
2007 Pan American Games in
Rio de Janeiro, in the first appearance of the marathon swimming, where she received the silver medal in the Women's 10K, the first Brazilian medal at this edition.[5][3]
She also swam at the 2008 Open Water World Championships in Seville, Spain.[6]
In 2009, Okimoto won the marathon swimming World Cup, winning 9 of 11 stages held, becoming the first Brazilian champion of the sport.[3]
At the
2009 World Aquatics Championships in
Rome, obtained the bronze medal. With that, she broke a 15 years-fast for Brazil in the World Championships, and became the first Brazilian woman to win a medal in the competition's history.[7] She was considered by Época magazine one of the 100 most influential Brazilians in 2009.[8]
In the
2012 Olympics in London Okimoto was unable to complete the race due to the water temperature, being disqualified.[2] The frustration that followed led Okimoto to clinical depression and thoughts of abandoning the sport, before being convinced otherwise by among others her husband-coach Ricardo Cintra.[13]
At the
2013 World Aquatics Championships, in
Barcelona, Poliana had a historical participation. She won the silver medal in the Women's 5K race,[14] and, some days later, became the World Champion in the 10K race.[15] Finishing, in the team event, she won the bronze medal with the Brazilian team, along with
Samuel de Bona and
Allan do Carmo.[16][17]
On August 12, 2013, Okimoto broke the Brazilian record in the 1500-metre freestyle, with a time of 16:26.90.[18]
Okimoto initially finished fourth at the
10 km race at the
2016 Olympics hosted by Brazil. A disqualification of second placed
Aurélie Muller upgraded her to the bronze, making Okimoto the first Brazilian woman to win a swimming Olympic medal.[21][22]
The following year, Okimoto wound up absent of the
2017 World Championships, finishing third in the national 10 km qualifiers and skipping the 5 km ones.[23][24]