She attained international prominence after scoring the title-winning penalty kick at the 2020 Summer Olympics, leading Canada to its first gold medal.

[17] On August 7, 2014, Grosso made her first junior appearance for Canada with the national under-15 against Puerto Rico in a 5–0 victory at the CONCACAF Girls Under-15 Championship.

[20] Canada would finish in third place at the tournament and Grosso was named to the Best XI, en route to qualification for the 2016 FIFA U-17 Women's World Cup.

[4] On January 18, 2018, Grosso made her debut for the under-20 team in a 3–1 victory over Costa Rica in the opening match of the 2018 CONCACAF Women's U-20 Championship.

[4] While Grosso did not feature in the first match, she came on as a ninetieth minute substitute for Janine Beckie in a 3–1 loss at Avaya Stadium in San Jose, California.

[33] She was by this point regarded as a rising talent, but had been continuing to have trouble finding her way into the starting lineup due to the presence of veteran Desiree Scott.

[33] Grosso scored the lone goal of the next game against Panama, in the process qualifying Canada for the 2023 FIFA Women's World Cup.

She was one of four players to score three goals in the tournament, but won the Golden Boot as top scorer due to having played the fewest minutes.

[7] During the group stage match against Ireland, with Canada down by a goal toward the end of what was generally judged a poor first half for the team, Grosso's cross into the box was deflected into the net by Irish defender Megan Connolly, tying the game.

[37] Canada was ultimately eliminated from the tournament after a 4–0 loss to Australia in their final group match; Grosso was substituted after the first half, having struggled defensively.