Juan Díaz (born September 17, 1983) is an American professional boxer who held the WBA (Unified), IBF and WBO lightweight championships from 2007 to 2008 and the IBO lightweight championship from 2008 to 2009.

Díaz maintained a full-time academic schedule while boxing, graduating high school from Contemporary Learning Center in Houston in 2001  and obtaining a bachelor's degree in political science from the University of Houston–Downtown. He is a community activist who has been deputized as a Volunteer Voter Registrar for Harris County, Texas, and has also worked with the League of Women Voters of the Houston Area to promote full participation in civic life. Diaz's promotional company, Baby Bull LLC, partners with ESPN Deportes to produce the radio show The Baby Bull Show, which has featured guest appearances by fellow boxers. He also has a trucking company, JD Express Inc, with his brother Jose as partner.

Juan Diaz Vs

Michael Lucero..................................Fight #06                                                                      Mahan Washington..........................Fight #08                                                                        Scott Buck...........................................Fight #11
Ubaldo Hernandez............................Fight #12
Juan Carlos Juarez...........................Fight #14                                                                   

Michael Davis.....................................Fight #16
Peter Nieves........................................Fight #17
Roy Delgado.......................................Fight #18
Arthur Cruz I.......................................Fight #19
John Baily............................................Fight #20

Eleazar Contreras Jr.........................Fight #21
Francisco Lorenzo............................Fight #22
Joel Perez............................................Fight #23

Martin O'Malley................................Fight #24
Lakva Sim............................................Fight #25
Julien Lorcy.........................................Fight #26
Arthur Cruz II......................................Fight #27
Fernando Angulo..............................Fight #31
Nate Campbell...................................Fight #34
 Michael Katsidis...............................Fight #35
Juan Manuel Márquez #1..............Fight #36
Paulie Malignaggi #1.......................Fight #37
Paulie Malignaggi #2.......................Fight #38
Juan Manuel Márquez #2..............Fight #39                                                                  Fernando Garcia................................Fight #45                                                                        Cesar Vasquez (Last Fight)............Fight #46