Antonio Margarito (born March 18, 1978) is a boxer from Tijuana, Mexico and is the current World Boxing Association Welterweight Champion. He is also a former International Boxing Federation and World Boxing Organization Welterweight champion.

On January 14, 1994, he beat Jose Trujillo in Tijuana by decision in four rounds, to make his professional debut at the age of 15. On April 25, he achieved his first knockout win, defeating Victor Angulo in the second round. On October 17, however, he suffered his first defeat, to Victor Lozoya, by decision in six. Over the course of his next six bouts, he lost two. However, he went onto a winning streak after that loss that has so far gone 28-2-1. He had notable wins over such fighters as Alfred Ankamah, Juan Soberanes, Sergio Gabriel Martinez and former Julio César Chávez rivals Buck Smith, David Kamau and Frankie Randall, a former World Jr. welterweight champion who became the first man to beat Chávez in 91 fights.
On July 21, 2001, he received his first world title try, against southpaw Santos, for the WBO world Welterweight crown, at Bayamon, Puerto Rico's Ruben Rodriguez Coliseum. The fight had to be stopped in the first round as a consequence of a clash of heads that opened deep gashes on both fighters and sent them both to a nearby hospital. Because the fight had not gone over four rounds or more for a technical decision to be awarded, it was declared a no contest, and Santos retained the belt but without adding a loss to Margarito's record.
At this point Margarito considered to go up in weight, to try to lure Fernando Vargas, Oscar de la Hoya or Shane Mosley into a lucrative fight, or Santos into a rematch at the Jr. Middleweight division. On October 17, 2003, Margarito made his Jr. Middleweight division debut with a two round knockout win over Maurice Brantley in Phoenix, Arizona.
On January 31, 2004, and back at the Welterweight division, he retained his title with a second round knockout of Canada's Hercules Kyvelos, who was undefeated until then.
Margarito did face Daniel Santos in a rematch on September 11 of the same year, at the Jose Miguel Agrelot Coliseum in San Juan, for Santos' WBO world Jr. Middleweight title. The rematch also ended because of a headbutt, but this time, as the fight had already reached the four rounds mark that is needed for fights like these to be decided by judges, Margarito lost by a split ten round technical decision. He was down on two scorecards when the fight was stopped.
On his next fight, April 23 of 2005, Margarito retained his WBO world Welterweight title against another Puerto Rican, undefeated world class puncher Kermit Cintron, dropping him four times on his way to a fifth round knockout. This was regarded as one of his best wins.
After almost a ten month layoff, Margarito returned to the boxing ring on February 18, 2006, retaining his title with a first round knockout of Manuel Gomez, who had lasted eleven rounds with Mosley for the IBF world Lightweight title eight and a half years before.
On December 2, 2006, Margarito defeated future champion Joshua Clottey via a twelve round unanimous decision. Margarito set a Compubox all-time record of 1675 total punches thrown in a twelve round bout.
On April 12, 2008, Margarito engaged in a rematch with Cintron, who had won the IBF welterweight title belt following his loss to Margarito in 2005. In the early rounds, Cintron struck Margarito with several flush power shots to the head, but Margarito remained unhurt and continued to execute a game plan of continuously moving forward and pressuring Cintron. In the sixth round, Margarito landed a liver shot to Cintron's midsection, knocking him out and taking the IBF title. As the referee counted Cintron out, HBO cameras captured Margarito, from a neutral corner, gesturing upward with his arms and urging Cintron to get up so that the two men could continue fighting for a longer period of time.
Following his successful rematch with Cintron, the IBF ordered him to fight a mandatory defense against the organization's number-one contender, Joshua Clottey, whom Margarito had previously defeated in 2006. Rather than agreeing to a rematch with Clottey, Margarito vacated the IBF title and agreed to a fight with undefeated WBA titlist Miguel Cotto of Puerto Rico. The Cotto-Margarito match took place on July 26, 2008, in Las Vegas, Nevada.
Margarito won in the 11th round via TKO. Margarito had lost almost all the early rounds, but he came back with relentless pace, eventually winning in the 11th round in which was one of the fights of the year. At the time of the TKO Margarito was ahead by two rounds on two judges' scorecards, with one judge having it even.
Margarito has a record of 37 wins, 5 losses and 1 no contest, with 27 wins by knockout.