Following disagreements with the president of the Puerto Rican boxing federation, Trinidad Sr. announced that he decided to turn his son into a professional boxer rather than wait for the 1992 Summer Olympics. The dispute between the boxer and the amateur federation began when the organization's president insisted that Trinidad move out of the 126 pound division in order to open a slot in the roster of the Puerto Rican National Team that was traveling to the Olympics games taking place in Barcelona, Spain.
Trinidad defended his title for the next three years against several opponents. Trinidad's first fight in Las Vegas, Nevada was against Héctor Camacho on January 29, 1994. He was cautious during the first rounds and received a cut over his left eye. In the third round he connected a solid combination that made Camacho change to a defensive stance. Throughout the fight Trinidad was on the offensive and won the fight by unanimous decision, in what was his first decision since he won the world championship. The scores awarded by the judges were 117–109, 116–110, and 119–106.
On September 17, 1994, Trinidad traveled to the MGM Grand for a second straight fight to compete in a title defense against Yori Boy Campas, who had a record of 56-0. In the second round Campas scored a knockdown, the second knockdown in Trinidad's career. Following this Trinidad exchanged several combinations, injuring Campas' face and breaking his nose. In the fourth round, the referee stopped the fight, the first defeat in Campas' career.
Trinidad's fourth fight outside Puerto Rico or the United States took place on Estadio de Beisbol in Monterey, Mexico. Trinidad was scheduled to defend his title against the undefeated Oba Carr. In the second round, Carr scored a knockdown, which was the product of a quick right hand punch. Trinidad continued the fight and pursued the challenger, who displayed a quick pace throughout the fight. In the fourth round Trinidad connected a solid punch that injured Carr, and in the eighth he scored three consecutive knockdowns before the referee stopped the fight by technical knockout.
Trinidad spent the next four years defending his title against numerous fighters in bouts televised on Showtime. Among these fights was a defense against Mahenge Zulu, the number two challenger for Trinidad's championship. This fight was part of a card that took place on April 3, 1998 in Bayamón, Puerto Rico and marked the first time that Trinidad had performed in the archipelago in five years. Trinidad began the first round by cautiously analyzing the challenger's style, but the round ended with quick exchanges after Zulu took the initiative in the offensive. In the second round Zulu was actively pursuing the champion, but retreated when he received a solid jab sequence. Early in the third round a series of jabs opened a wound on Zulu's mouth, while the challenger's punches were not reaching their target. Trinidad began the fourth round heavily on in the offensive connecting several combinations which hurt the challenger, using this to land more punches in Zulu's head and body. One punch hit Zulu in the jaw, he fell to the floor and tried to rise, but the referee stopped the fight before he could do so.
On February 20, 1999, Trinidad defended the welterweight championship against Pernell Whitaker, winning the fight by unanimous decision in a contest that marked his thirteenth successful defense. The fight began with both boxers displaying aggressive styles, which included excessive pushing. In the following rounds both boxers used their jabs most of the time with Trinidad gaining a advantage when Whitaker attempted to attack inside, eventually scoring a knockdown in round two. In the fourth, fifth and sixth rounds the fighters exchanged combinations. Later in the fight both boxers fell to the floor in what were ruled as "accidental slips." On the seventh round Whitaker displayed more offense, trading power punches with Trinidad, but the champion retained control in the fight's tempo during the eight, ninth, and tenth rounds. In the last round Whitaker, with a badly swollen right eye, displayed a purely defensive stance, avoiding his opponent throughout the round while Trinidad continued on the offensive until the fight concluded. The judges gave the champion scores of 117–111, 118–109 and 118–109.
In the spring of 1999, Don King and Oscar De la Hoya's promoter, Bob Arum, agreed to co-promote a mega-fight for the World Boxing Council and International Boxing Federation welterweight championships on September 18, 1999 at the Mandalay Bay Hotel in Las Vegas. Early in the fight De la Hoya employed boxing to connect combinations while avoiding Trinidad's attacks. The second round began with both boxers trading punches but De la Hoya quickly returned to his previous tactic, which he employed in the third round. In the fourth round Trinidad pressured the offense while De la Hoya tried to avoid his punches by moving, both boxers eventually exchanged punches. In the fifth round Trinidad continued in the offensive while De la Hoya attempted to remain on the outside corners of the ring, Trinidad's eye was swollen following a trade of punches. In the sixth round Felix connected a solid right to his opponent's jaw. Trinidad began the seventh round connecting several solid left hooks to the body that affected De la Hoya's stamina. In the eighth round the swelling on Trinidad's eye was reduced and he was able to control the center of the ring. After trading several combinations in the ninth round, Trinidad began to control the fight's tempo in the tenth, countering his adversary's attacks. Thinking that they had an advantage on points, De la Hoya's corner urged him to be conservative, a strategy benefiting Trinidad who became more active in the offensive, connecting several solid combinations. Both boxers continued this pattern in the final round, with De la Hoya trying to slow down the offense while displaying signs of exhaustion, as Trinidad continued to possess control. The judges gave Trinidad a majority decision, with scores of 115–113, 115–114 and 114–114.
On December 2, 2000, he was scheduled to fight in a unification card against Fernando Vargas, the International Boxing Federation's junior middleweight champion. The fight began in a fast pace with Trinidad connecting a solid combination that led to his opponent being kocked down. Vargas was able to stand up, but another combination injured him a second time and led to another knockdown. Early in the second round Trinidad was in the offensive but Vargas connected a solid combination at the round's closing moments which opened a cut over Trinidad's right eye. In the fourth round's opening seonds one of Vargas' punches connected on Trinidad's jaw and he fell, marking the eight knockdown in his career. In the fifth round Vargas was in control of the fight's offensive, connecting combinations to Trinidads' body. In the sixth round Trinidad regained control of the fight's tempo that lasted throughout the contest, connecting punches on Vargas' head and left jabs to the ribs. In the eighth, Vargas displayed signs of exhaustion which slowed his offensive while Trinidad then pursued the offense with combinations to the body. This pattern continued throughout the ninth, tenth and eleventh rounds. Opening the final round Vargas was on the offensive, connecting a solid left hook. Trinidad countered the attack with a left hook that made Vargas collapse; Vargas was able to stand up, but was subsequently knocked down for a second time. With Vargas injured, Trinidad continued connecting combinations, until the referee stopped the fight by technical knockout.
Following his fight with Vargas, Trinidad moved up in weight – this time to participate in Don King's middleweight unification tournament featuring IBF champion Bernard Hopkins, WBA champion William Joppy, and WBC champion Keith Holmes. Trinidad was matched with Joppy, whom he defeated by technical knockout in the fifth round of a contest that took place on May 12, 2001. Joppy opened the first round on the offensive, but late in the round Trinidad scored a knockdown with a combination of punches that came close to throwing Joppy underneath the ropes. Trinidad subsequently scored a knockdown in the fourth round, during this stage of the competition he was using combinations of left hooks and right punches to the head. In the fifth round Trinidad scored another knockdown, Joppy attempted to continue the fight, but while he was using the ropes to help him stand, the referee stopped the fight. When the contest was over, Trinidad explained his strategy by stating: "I knew he wanted to impose his will, his weight, and I wouldn't let him do it".
The middleweight unification fight between Hopkins and Trinidad was originally scheduled for September 15, 2001, at the Madison Square Garden. On the morning of September 11, terrorists attacked the World Trade Center. Following this incident, the fight was postponed indefinitely. After receiving assurances from Madison Square Garden officials and the City of New York, Don King rescheduled the fight for September 29. The pace of the fight in the early rounds was slow, with each boxer studying his opponent. In the second round Hopkins connected some combinations while Trinidad pursued the offensive in the fourth round and both boxers traded sequences of punches. This pattern continued in the fifth round with Trinidad showing a aggressive style while Hopkins relied on jabs. In the sixth Trinidad continued an offensive stance and won the round after trading several combinations. Both fighters continued to exchange punches in the eighth and ninth round with Hopkins connecting three consecutive solid punches. In the twelfth round Hopkins' scored a knockdown, but before the contest could continue Trinidad's father entered the ring, which led to the referee stopping the fight by technical knockout. According to an interview with Bernard's trainer Bouie Fisher, prior to the fight members of Hopkins' team visited the Trinidad dressing room in what is considered a normal boxing custom to watch the taping of Trinidad's hands before his gloves were placed on. The Hopkins camp claimed that Trinidad's hands were wrapped in an incorrect fashion, and threatened to cancel the fight unless they were wrapped correctly. Fisher also stated that the Chief Inspector of the NYSAC insisted to Trinidad's camp that they needed to re-wrap his hands in a correct fashion.
Trinidad was subsequently scheduled to fight against Hacine Cherifi in a contest that he won by technical knockout in the fourth round. The event was part of a card that took place on May 11, 2002, and was organized in San Juan, Puerto Rico. Early in the first round Trinidad's strategy consisted of using his jab while Cherifi did not try to directly engage in the offensive. In the last minute of the round a punch by Trinidad hit Cherifi's chin leaving him disoriented, he followed this with a combination and scored a knockdown. In the second round, Trinidad displayed more boxing and was on the offensive by using combinations to the head and ribs. In the third Cherifi landed more punches than in the previous two, but Trinidad relied on throwing left jabs. One of his punches hit Cherifi's liver, followed by a punch to the jaw, making Cherifi fall to the floor. In the fourth, a series of combinations injured Cherifi, who collapsed to the floor twice, forfeiting the fight on the second occasion. Following this contest Trinidad announced his retirement, at the moment leaving the sport with a record of 41 wins, one defeat, and 34 wins by knockout.
On May 14, 2005, Trinidad competed against Winky Wright, in a fight where the winner would become the World Boxing Council's number one challenger in the Middleweight division. Wright won the fight by decision, receiving scores of 120–107 and 119–108 twice by the judges. Trinidad's fighting style appeared to be out of rhythm in the first round, while Wright presented a defensive stance and relied on jabs. During the first three rounds Wright was in the offensive scoring with jabs. On the fourth round Trinidad connected a solid combination. In the sixth, Wright continued the strategy used in the previous rounds while Trinidad employed a strategy where he tried to neutralize his opponent's punches by standing in front of him. In the later rounds Trinidad tried to take the contest's offensive but his adversary managed to block most of his punches while continuing his previous tactic. In the twelfth round Trinidad pursued Wright while trying to score a knockout, but his opponent boxed away from him until the round ended. Following this fight, Trinidad retired temporarily, after his father informed him that he would not continue in his corner.
Trinidad came out of his second retirement for the fight against Roy Jones, a former four-division champion on January 19, 2008. According to the contract, it was to be at a catch weight of 170lbs; and was broadcast live on HBO Pay-Per-View. The card took place at Madison Square Garden in New York city.
Trinidad began the fight on the offensive and won the first two rounds. The third and fourth rounds were won by Jones who relied on the velocity of his punches. This pattern continued in the fifth and sixth rounds. In the seventh round, Jones scored a knockdown following a right hand. Following this Jones continued to use his speed while Trinidad pursued the offensive, in the tenth round Jones scored a second knockdown after landing a combination. The judges declared the fight a unanimous decision in favor of Jones with scores of 117–109 and 116–110 twice.
Félix Trinidad was born in Fajardo, Puerto Rico, to Irma García and Félix Trinidad Senior. During his childhood the family moved to Cupey Alto, a subdivision of San Juan, Puerto Rico, where he grew up. His future wife, Sharon Santiago, lived in Cupey and first met Trinidad in the home of her neighborhood friend, a classmate of Trinidad's. Trinidad pursued a relationship with Santiago, including an attempt to impress her with his red Ford Mustang. He continued to press for her affection and, with the help of Santiago's neighbor, Trinidad was able to win her over. Early on, Santiago's mother thought that Trinidad was related to her daughter's friend, but she realized the true situation when she visited the friend's house and he acted nervous in her presence. Santiago's father objected to the relationship because Trinidad was an athlete; at the time many athletes had a negative public image. Santiago became rebellious, but Trinidad eventually won her family's trust. The couple was married four years after they began dating and have had four daughters. Trinidad has a fifth daughter, named Alondra Nicole, from another relationship.