[3] Alan Núñez began his career in the youth divisions of Club Cerro Porteño, where he excelled as a right-back.
In 2022, he was promoted to the first team and made his debut on May 15, 2022, in a Paraguayan Primera División match, a 2-1 loss against Sol de América.
[4] In 2023, he participated in the U-20 Copa Libertadores held in Chile with Cerro Porteño's youth team, finishing in third place.
[5] That same year, he was called up to the Paraguay national under-20 football team to play in the South American U-20 Championship held in Colombia.
In 2024, he won the CONMEBOL Pre-Olympic Tournament held in Venezuela,[6] securing Paraguay's qualification for the 2024 Summer Olympics.