Alonso Martínez

On 18 August 2021, Martínez joined Belgian First Division B club Lommel on a five-year deal, returning to Alajuelense until the end of the year.

New York City FC

On 4 August 2023, it was announced that Martínez had signed with Major League Soccer club New York City FC. On 31 May 2024, Martinez came on as a substitute and scored a 10-minute hat-trick in a 5–1 win vs San Jose Earthquakes. Martinez had a breakout season with NYCFC with his scoring displays. Despite playing a winger for most of his career, New York City FC coach Nick Cushing decided to play Martinez as a striker; Martinez had a career high 16 goals in the 2024 MLS Season and helped guide NYCFC into the playoffs after missing out in 2023.

Martínez was called up to the Costa Rica national team on 9 May 2021 for the 2021 CONCACAF Nations League Finals, and was included in the final 23 on 25 May. He made his debut on 3 June 2021 in a semi-final against Mexico. He had also played for the U-23 team for the 2020 Summer Olympics qualifying, debuting on 18 March 2021, with a 1–0 defeat to the United States U-23.

Club

As of match played 18 October 2025

International

As of match played 13 November 2025

International goals

Alajuelense

Liga FPD: Apertura 2020 CONCACAF League: 2020