Belmonte qualified for the 2020 Summer Olympics (held in July and August 2021 due to the COVID-19 pandemic) in the 800-metre freestyle and the 1500-metre freestyle at the 2020 Open Castalia Castelión held in Castellón, Spain in December 2020. In May 2021 Belmonte was officially confirmed by the Spanish Olympic Committee as one of two flag bearers for Spain at the Opening Ceremony of the 2020 Summer Olympics in Tokyo, Japan on 23 July 2021.