Melillo played in the youth ranks of Peñarol Infantil Olmos, before continuing his career with Villa San Carlos.[2] Ten goals in fifty-five appearances arrived in three Primera B Metropolitana seasons from 2009–10, which included a hat-trick over Tristán Suárez on 11 August 2011.[1][3] In July 2012, Melillo joined Primera División side Racing Club on loan.[4] He didn't feature in 2012–13, a season which his parent club ended with promotion to Primera B Nacional; where he'd appear twenty-three times as they were relegated back down.[1][5]Central Norte became Melillo's third team in 2015, which preceded him signing for San Telmo in 2016.[1]
After participating in sixty games and netting nine goals across two campaigns, Melillo completed a move to Almirante Brown on 13 June 2018.[1][6][7] His debut came in a defeat to Estudiantes on 20 August, which was followed by his first goal against All Boys in September.[1][8] July 2019 saw Melillo head across Primera B Metropolitana to Tristán Suárez.[9] He scored five goals in twenty-one games in his first season there.[1]