Martínez began representing Paraguay at the
under-17 level, featuring in the
2024 and
2025 editions of the
South American U-17 Women's Championship, and finishing as the top scorer in the latter. In August 2024, she was named in
Paraguay's squad for the
2024 FIFA U-20 Women's World Cup in
Colombia, where she appeared in all three group stage matches. In July 2024, Martínez received her first call-up to the
senior national team for friendly matches against
Chile. She made her senior debut on 12 July 2024, scoring a consolation goal in a 1–4 defeat to the visitors. A year later, she was named in Paraguay's final squad for the
2025 Copa América Femenina, as the youngest player in the team. On 13 July 2025, she made her debut in the competition as a starter and scored a hat-trick against
Bolivia, becoming the youngest player to score multiple goals in a single match at the competition over the last three editions. In doing so, she broke the previous record held by
Deyna Castellanos.
International goals Paraguay score listed first, score column indicates score after each Martínez goal ==Honours==