Facundo Diaz Acosta was born in Buenos Aires, Argentina, on December 15, 2000, to his parents, Pedro and Cecilia. The Argentinian player started playing tennis at age three and he credits his grandparents with introducing him to the sport.
Diaz Acosta began his professional tennis career at Futures level, often playing events in Argentina. Before turning professional, he reached number six in the junior rankings. He also achieved silver at the Youth Olympic Games in 2018 and gold in the doubles alongside Sebastian Baez.
By 2019, Diaz Acosta was playing in regular Futures and Challenger competitions. In 2020, he made his ATP Tour debut at the Argentina Open. The Argentinian competed in the singles and doubles events, but lost in round one in both draws.
Diaz Acosta continued to develop at the Challenger level in 2021 and he progressed to two quarter-final stages in Prague and Sao Paulo. He also made the Argentina Open main draw for a second consecutive season but lost again in the first round.
Despite not making any ATP main draws in 2022, Diaz Acosta performed well at Challenger events. He made five finals at this level and lifted his first-ever Challenger title at the 2022 Copa Seville, defeating compatriot Román Andres Burruchaga in the final.
By 2023, Diaz Acosta was regularly qualifying for ATP Tour events. At the 2023 Argentina Open, Diaz Acosta won his first main draw match, beating Federico Coria in round one. In the second half of the season, Diaz Acosta made his Grand Slam debut at the Roland Garros before progressing to the US Open main draw. However, the Argentinian lost in round one at both events.
Diaz Acosta started 2024 in fine form and played his first-ever Australian Open match in January. He then followed this feat with a quarter-final run at the Cordoba Open before making his first-ever ATP event final at the 2024 Argentina Open.
In the final, Diaz Acosta lost to Nicolas Jarry in straight sets. One month later, Diaz Acosta made his Masters debut at the Miami Open. He also produced a strong display at the Barcelona Open, progressing to the quarter-finals.
