Born in Madrid on 4 June 2004, he is a regular call-up for the Spanish national team. He developed in Real Madrid's youth academy before moving to Germany with Ratiopharm Ulm, a stepping stone before advancing his career by signing for Barça.
The 20-year-old, 1.94-metre point guard has a contract with the club for three seasons, until 30 June 2027. At Real Madrid, Núñez was named MVP of the Junior EuroLeague, averaging 9.5 points and 5 assists. During the 2020-21 season, he made the leap to the first team, playing a total of 15 games, the last one in the final against Barça in 2022. That year, he left in search of more playing time to continue growing and evolving with Ratiopharm Ulm, his first experience abroad.
The Spanish international finished the second of his two seasons in Germany with an average of 9.6 points, 3.5 rebounds, and 4.7 assists during the Bundesliga regular season, while in the playoffs he averaged 7.3 points, 3.8 rebounds, and 4 assists per game. In the EuroCup, his averages were 10.8 points, 3.6 rebounds, and 5.7 assists.
Núñez has become a key player and contributed to the growth of Ratiopharm Ulm, with whom he won the Bundesliga championship in the 2023/24 season, the first time in their history that they won the German League, overcoming Baskets Bonn in the final.
Before joining Barça, Juan Núñez tried his luck in the NBA draft. He was a 36th pick for the Indiana Pacers, but his rights were eventually traded to the San Antonio Spurs.
