At the 2017 World Aquatics Championships in Budapest, in the Men's 4 × 100 metre freestyle relay,
the Brazilian team composed of Santos, César Cielo, Bruno Fratus and Marcelo Chierighini achieved a historic result by winning the silver medal, the best Brazilian result of all time at the World Championships in this race. Brazil beat the South American record of 2009, still in the super-suits era, with a time of 3:10.34, just 0.28 from the US team. The last medal of Brazil in this race, in Worlds, was obtained in 1994.[3][4][5] He also finished 14th in the Men's 100 metre freestyle.[6]
At the 2018 Pan Pacific Swimming Championships in Tokyo, Japan, he won the gold medal in the Men's 4 × 100 metre freestyle relay, along with Marcelo Chierighini, Marco Ferreira Júnior and Pedro Spajari.[7] He also finished 12th in the Men's 100 metre freestyle[8] and 12th in the Men's 50 metre freestyle.[9]
In February 2020, the Court of Arbitration for Sport (CAS) issued a final judgement that Santos had committed an anti-doping rule violation for unintentional use of clostebol as a consequence of "cross-contamination through the sharing of bathroom towels ... with a family member who had been using Clostebol under medical prescription".[10] He had been earlier issued with a 12-month suspension by FINA, but this was overturned by the CAS ruling.[11] Nevertheless, it was reported that Santos was still indefinitely banned from competing in the International Swimming League due their policy of barring swimmers who have ever received even a provisional suspension.[12]
In June 2021, he qualified to represent Brazil at the 2020 Summer Olympics.[13]
