On June 16, 2021, Martens was named as one of the Netherlands' 18 first-team players at the 2020 Olympics, the Netherland women's first ever Olympics tournament. In the first match of the group stages, Martens scored her 50th national team goal against Zambia. Martens scored another in that match with the final result being Zambia 3–10 Netherlands, the highest scoring women's football match in Olympics history. In the Netherlands' third and final group stage match, Martens scored another two goals against China as the Dutch advanced to the quarterfinals of the tournament. They faced their 2019 Women's World Cup Final rivals the United States, where Martens missed a penalty in the 81st minute and the Dutch were defeated after a penalty shootout following a period of extra time.