| No. | Result | Record | Opponent | Type | Round, time | Date | Location | Notes |
| 45 | Loss | 39–6 | Manny Pacquiao | RTD | 8 (12), 3:00 | Dec 6, 2008 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | |
| 44 | Win | 39–5 | Steve Forbes | UD | 12 | May 3, 2008 | Home Depot Center, Carson, California, U.S. | |
| 43 | Loss | 38–5 | Floyd Mayweather Jr. | SD | 12 | May 5, 2007 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Lost WBC light middleweight title |
| 42 | Win | 38–4 | Ricardo Mayorga | TKO | 6 (12), 1:25 | May 6, 2006 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Won WBC light middleweight title |
| 41 | Loss | 37–4 | Bernard Hopkins | KO | 9 (12), 1:38 | Sep 18, 2004 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Lost WBO middleweight title;For WBA (Undisputed), WBC, IBF, and The Ring middleweight titles |
| 40 | Win | 37–3 | Felix Sturm | UD | 12 | Jun 5, 2004 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Won WBO middleweight title |
| 39 | Loss | 36–3 | Shane Mosley | UD | 12 | Sep 13, 2003 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Lost WBA (Unified), WBC, IBA, and The Ring light middleweight titles |
| 38 | Win | 36–2 | Yori Boy Campas | TKO | 7 (12), 2:54 | May 3, 2003 | Mandalay Bay Events Center, Paradise, Nevada, U.S. | Retained WBA (Unified), WBC, IBA, and The Ring light middleweight titles |
| 37 | Win | 35–2 | Fernando Vargas | TKO | 11 (12), 1:48 | Sep 14, 2002 | Mandalay Bay Events Center, Paradise, Nevada, U.S. | Retained WBC light middleweight title;Won WBA (Unified), IBA, and vacant The Ring light middleweight titles |
| 36 | Win | 34–2 | Javier Castillejo | UD | 12 | Jun 23, 2001 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Won WBC light middleweight title |
| 35 | Win | 33–2 | Arturo Gatti | TKO | 5 (12), 1:16 | Mar 24, 2001 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | |
| 34 | Loss | 32–2 | Shane Mosley | SD | 12 | Jun 17, 2000 | Staples Center, Los Angeles, California, U.S. | Lost WBC and IBA welterweight titles |
| 33 | Win | 32–1 | Derrell Coley | KO | 7 (12), 3:00 | Feb 26, 2000 | Madison Square Garden, New York City, New York, U.S. | Won vacant IBA welterweight title |
| 32 | Loss | 31–1 | Félix Trinidad | MD | 12 | Sep 18, 1999 | Mandalay Bay Events Center, Paradise, Nevada, U.S. | Lost WBC welterweight title;For IBF welterweight title |
| 31 | Win | 31–0 | Oba Carr | TKO | 11 (12), 0:55 | May 22, 1999 | Mandalay Bay Events Center, Paradise, Nevada, U.S. | Retained WBC welterweight title |
| 30 | Win | 30–0 | Ike Quartey | SD | 12 | Feb 13, 1999 | Thomas & Mack Center, Paradise, Nevada, U.S. | Retained WBC welterweight title |
| 29 | Win | 29–0 | Julio César Chávez | RTD | 8 (12), 3:00 | Sep 18, 1998 | Thomas & Mack Center, Paradise, Nevada, U.S. | Retained WBC welterweight title |
| 28 | Win | 28–0 | Patrick Charpentier | TKO | 3 (12), 1:56 | Jun 13, 1998 | Sun Bowl, El Paso, Texas, U.S. | Retained WBC welterweight title |
| 27 | Win | 27–0 | Wilfredo Rivera | TKO | 8 (12), 2:48 | Dec 6, 1997 | Boardwalk Hall, Atlantic City, New Jersey, U.S. | Retained WBC welterweight title |
| 26 | Win | 26–0 | Héctor Camacho | UD | 12 | Sep 13, 1997 | Thomas & Mack Center, Paradise, Nevada, U.S. | Retained WBC welterweight title |
| 25 | Win | 25–0 | David Kamau | KO | 2 (12), 2:54 | Jun 14, 1997 | Alamodome, San Antonio, Texas, U.S. | Retained WBC welterweight title |
| 24 | Win | 24–0 | Pernell Whitaker | UD | 12 | Apr 12, 1997 | Thomas & Mack Center, Paradise, Nevada, U.S. | Won WBC welterweight title |
| 23 | Win | 23–0 | Miguel Ángel González | UD | 12 | Jan 18, 1997 | Thomas & Mack Center, Paradise, Nevada, U.S. | Retained WBC super lightweight title |
| 22 | Win | 22–0 | Julio César Chávez | TKO | 4 (12), 2:37 | Jun 7, 1996 | Caesars Palace, Paradise, Nevada, U.S. | Won WBC super lightweight title |
| 21 | Win | 21–0 | Darryl Tyson | KO | 2 (10), 2:38 | Feb 9, 1996 | Caesars Palace, Paradise, Nevada, U.S. | |
| 20 | Win | 20–0 | Jesse James Leija | RTD | 2 (12), 3:00 | Dec 15, 1995 | Madison Square Garden, New York City, New York, U.S. | Retained WBO lightweight title |
| 19 | Win | 19–0 | Genaro Hernández | RTD | 6 (12), 3:00 | Sep 9, 1995 | Caesars Palace, Paradise, Nevada, U.S. | Retained WBO lightweight title |
| 18 | Win | 18–0 | Rafael Ruelas | TKO | 2 (12), 1:43 | May 6, 1995 | Caesars Palace, Paradise, Nevada, U.S. | Retained WBO lightweight title;Won IBF lightweight title |
| 17 | Win | 17–0 | John John Molina | UD | 12 | Feb 18, 1995 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Retained WBO lightweight title |
| 16 | Win | 16–0 | John Avila | TKO | 9 (12), 1:07 | Dec 10, 1994 | Grand Olympic Auditorium, Los Angeles, California, U.S. | Retained WBO lightweight title |
| 15 | Win | 15–0 | Carl Griffith | TKO | 3 (12), 1:02 | Nov 18, 1994 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Retained WBO lightweight title |
| 14 | Win | 14–0 | Jorge Páez | KO | 2 (12), 0:39 | Jul 29, 1994 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Won vacant WBO lightweight title |
| 13 | Win | 13–0 | Giorgio Campanella | TKO | 3 (12), 2:22 | May 27, 1994 | MGM Grand Garden Arena, Paradise, Nevada, U.S. | Retained WBO junior lightweight title |
| 12 | Win | 12–0 | Jimmi Bredahl | RTD | 10 (12), 3:00 | Mar 5, 1994 | Grand Olympic Auditorium, Los Angeles, California, U.S. | Won WBO junior lightweight title |
| 11 | Win | 11–0 | Narciso Valenzuela | KO | 1 (10), 2:25 | Oct 30, 1993 | America West Arena, Phoenix, Arizona, U.S. | |
| 10 | Win | 10–0 | Angelo Nunez | RTD | 4 (10), 3:00 | Aug 27, 1993 | Wilshire Hotel, Beverly Hills, California, U.S. | |
| 9 | Win | 9–0 | Renaldo Carter | TKO | 6 (10), 2:10 | Aug 14, 1993 | Casino Magic, Bay St. Louis, Mississippi, U.S. | |
| 8 | Win | 8–0 | Troy Dorsey | RTD | 1 (10), 3:00 | Jun 7, 1993 | Thomas & Mack Center, Paradise, Nevada, U.S. | |
| 7 | Win | 7–0 | Frank Avelar | TKO | 4 (10), 2:00 | May 8, 1993 | Caesars Tahoe, Stateline, Nevada, U.S. | |
| 6 | Win | 6–0 | Mike Grable | UD | 8 | Apr 6, 1993 | Blue Cross Arena, Rochester, New York, U.S. | |
| 5 | Win | 5–0 | Jeff Mayweather | TKO | 4 (8), 1:35 | Mar 13, 1993 | Las Vegas Hilton, Winchester, Nevada, U.S. | |
| 4 | Win | 4–0 | Curtis Strong | TKO | 4 (6), 1:40 | Feb 6, 1993 | Sports Arena, San Diego, California, U.S. | |
| 3 | Win | 3–0 | Paris Alexander | TKO | 2 (6), 1:52 | Jan 3, 1993 | Hollywood Palladium, Los Angeles, California, U.S. | |
| 2 | Win | 2–0 | Clifford Hicks | KO | 1 (6), 1:17 | Dec 12, 1992 | America West Arena, Phoenix, Arizona, U.S. | |
| 1 | Win | 1–0 | Lamar Williams | KO | 1 (6), 2:12 | Nov 23, 1992 | Great Western Forum, Inglewood, California, U.S. | |