Pereiro grew from the youth system of Nacional. In April 2012, along with Diego Baldi, Leandro Otormín and Rodrigo Amaral, he traveled to England to participate in a ten-day training session at Liverpool.[4]
On 15 July 2015, Eredivisie side PSV Eindhoven confirmed the signing of Pereiro on a five-year deal. He was given the number 7 jersey, previously worn by Memphis Depay, and made his official debut in the Dutch Super Cup 2015, coming on as a substitute for Adam Maher.[6] On 4 October 2015, Pereiro made his first start for PSV Eindhoven, scoring a brace in a 2–1 victory against arch-rival Ajax.[7] Pereiro then scored his first hat-trick for the club on 27 October 2015, in a KNVB Cup fixture against Genemuiden.[8]
He scored the first goal as PSV beat rivals Ajax 3–0 to clinch the 2017–18 Eredivisie title.[9]
On 31 January 2020, he signed a 4.5-year contract with Italian club Cagliari.[10] On 17 January 2023, Pereiro returned to Nacional on loan until the end of the 2022–23 season.[11] On 18 January 2024, Pereiro moved on a new loan to Ternana.[12] On 29 August 2024, his contract with Cagliari was terminated by mutual consent.[13] On 14 October 2024, he join Genoa as free agent.[14]
He was called up to the full Uruguay squad in the autumn of 2017.[15] He made his debut in a 0-0 draw against Poland at the Stadion Narodowy in Warsaw on 10 November 2017.[16]