Born in England, Brereton Díaz represented his birth country at the under-19 and under-20 levels, before being named in the Chile squad for the 2021 Copa América in Brazil, having qualified for the latter through his mother.
[13] On 27 March 2017, having made ten appearances and scoring against Fulham and Brentford, Brereton Díaz was nominated for the Championship Apprentice of the Year award.
[24][25] On 5 January 2024, Brereton Díaz returned to England on loan until the end of the season with Premier League relegation-struggling side Sheffield United.
In March 2017, Brereton Díaz received his first call-up to an England side after being named in the under-19s squad for games against their Spanish, Norwegian and Belarusian counterparts.
Having started his side's 3–0 defeat of Spain and coming off the bench for the 5–1 beating of Belarus, manager Keith Downing praised his performances and ease at settling into the squad.
[39] Brereton Díaz also played at the 2018 UEFA European Under-19 Championship, scoring his only goal of the tournament in the opening group stage match against Turkey.
[40] After noticing he was half Chilean whilst playing Football Manager, a group of fans began a social media campaign to get Brereton Díaz picked for Chile.
[41] This was subsequently picked up by the national media and on 24 May 2021, Brereton Díaz was called up to the Chile squad for the first time by manager Martín Lasarte for the 2022 FIFA World Cup qualifiers against Argentina and Bolivia.
[45] In March 2024, he was dropped by Chilean coach Ricardo Gareca due to his lack of Spanish language skills,[46] but later in June 2024 he was called up for the 2024 Copa América.