Martens was selected in the final squad for the 2019 FIFA Women's World Cup in France, despite the fact that her large toe was injured. She scored both Dutch goals in a 2–1 victory over Japan in the round of 16, the second from a controversial VAR-awarded penalty. When celebrating her last-minute winner against Japan, teammate Jill Roord stepped on her foot and aggrivated her toe injury. Martens didn't train before the Netherlands' upcoming quarterfinal match against Italy. Despite her worsening injury, she started against Italy and played all 90 minutes in the match, which ended Italy 0–2 Netherlands. In the Netherlands' following semifinal match against Sweden, she started but was substituted out because of the pain she felt in her toe from the beginning of the match. Thanks to a goal in extra time from Jackie Groenen, the Dutch made it to their first ever Women's World Cup final against the United States. Martens trained separately from the rest of the Netherlands squad ahead of the final, and starting the final was going to be a "gameday decision" as manager Sarina Wiegman was not particularly confident about the evolution of Marten's injury. Martens started the 2019 Women's World Cup Final regardless, but had a hard head-to-head collision with United States defender Kelley O'Hara that caused them to both be down on the pitch for a few minutes. Martens continued to play to the second half, but after the Netherlands conceded two goals within ten minutes, she was subbed off for Jill Roord in the 70th minute. The score kept to full time, and the Dutch lost the final 2–0.