At the 2019 World Championships, Moellhausen was the only non-top-16 female epee fencer to reach the final four. She won her first two matches comfortably, beating Poland’s Renata Knapik-Miazga 15-12 in the first round, and China’s Mingye Zhu 15-10 in the second. She won her round of 16 against Italy’s Alberta Santuccio. Moellhausen led throughout all the match and eventually won, 15-14. After a dramatic 11-10 extra time win over Lis Röttler-Fautsch from Luxembourg in the quarterfinals, she overcame No. 3 seed Vivian Kong from Hong Kong, China in the semis, 15-9. She finally won the final in extra time 13–12 against World No. 11, Sheng Lin from China to claim her first individual World Champion title, and the first ever medal at a World Fencing Championship for Brazil.