Joseph Diaz has eight losses against eight opponents on his boxing record. For a list of Diaz's best fights, refer to "Best fights of Joseph Diaz".
On August 2, 2025 Joseph Diaz faced off against Regis Prograis in a lightweight bout at age 32. He was coming in with a record of 33-8-1 (15), and Prograis was 36 years old and with a record of 29-3 (24). Diaz lost the fight via 10-round unanimous decision.
On November 9, 2024 Joseph Diaz faced off against Abraham Montoya in a lightweight bout at age 31. He was coming in with a record of 33-7-1 (15). Diaz lost the fight via 10-round split decision.
On April 27, 2024 Joseph Diaz faced off against Oscar Duarte in a super-lightweight bout at age 31. He was coming in with a record of 33-6-1 (15), and Duarte was 28 years old and with a record of 26-2-1 (21). Diaz lost the fight via 9th-round KO.
On February 15, 2024 Joseph Diaz faced off against Jesus Antonio Perez Campos in a lightweight bout at age 31. He was coming in with a record of 33-5-1 (15). Diaz lost the fight via 10-round split decision.
On March 18, 2023 Joseph Diaz faced off against Mercito Gesta in a lightweight bout at age 30. He was coming in with a record of 32-4-1 (15), and Gesta was 35 years old and with a record of 33-3-3 (17). Diaz lost the fight via 10-round split decision.
On October 29, 2022 Joseph Diaz faced off against William Zepeda in a lightweight bout at age 29. He was coming in with a record of 32-3-1 (15), and Zepeda was 26 years old and with a record of 26-0 (23). Diaz lost the fight via 12-round unanimous decision.
On December 4, 2021 Joseph Diaz fought Devin Haney in a lightweight world-title fight for Haney's WBC title. Diaz was 29 years old and with a record of 32-2-1 (15), and Haney was 23 years old and with a record of 26-0 (15). Diaz lost the fight via 12-round unanimous decision.
On May 19, 2018 Joseph Diaz fought Gary Russell Jr. in a featherweight world-title fight for Russell Jr.'s WBC title. Diaz was 25 years old and with a record of 26-1 (14), and Russell Jr. was 29 years old and with a record of 28-1 (17). Diaz lost the fight via 12-round unanimous decision.