On 3 December 2014 at the 12th FINA World Swimming Championships in Doha, Qatar, Belmonte won two gold medals. One in the 200-metre butterfly and one in the 400-metre individual medley. At the same time she achieved the world record with substantial time improvements, making her the first female swimmer to go under 2 minutes in the 200-metre butterfly with her time of 1:59.61. Belmonte lowered the world record by 1.17 seconds and finished ahead of second place finisher Katinka Hosszú by more than 1.5 seconds. She also set a new world record with her gold medal winning time of 4:19.86 in the 400-metre individual medley, lowering the world record by 99 hundredths of a second and finishing over 3 seconds ahead of second place finisher Katinka Hosszú.