During his tenure at the Peruvian Congress, he became the second openly gay congressman, and led numerous bills in favor of the LGBT community in Peru.

[7] Following the completion of his law degree, de Belaúnde was hired as Cabinet Head of the Municipality of Miraflores, overseeing the advisory role of the district.

[16] In addition to his LGBT agenda, de Belaúnde is one of the authors of the medical cannabis bill, along with Congresswoman Tania Pariona from New Peru.

De Belaúnde left the parliamentary caucus on 26 December 2017, in protest to the pardon granted to former president Alberto Fujimori by President Pedro Pablo Kuczynski, considering that the pardon was processed in a political and non-humanitarian way, as there was suspicion as result of a deal between the government and the Fujimorist faction led by Kenji Fujimori in order to prevent Kuczynski's removal from office.

[17] Following Kuczynski's resignation and Martín Vizcarra ascension to the presidency, de Belaúnde remained an independent until 19 December 2018, as he joined the Liberal Bench, a parliamentary caucus made up of Gino Costa, Vicente Zeballos, Guido Lombardi, and Francesco Petrozzi.