Leonard started boxing at the Palmer Park Recreation Center in 1969. His older brother, Roger, started boxing first. Roger helped start the boxing program, urging the center’s director, Ollie Dunlap, to form a team. Dave Jacobs, a former boxer, and Janks Morton volunteered as boxing coaches. Roger won some trophies and showed them off in front of Ray, goading him to start boxing.

In 1972, Leonard boxed in the featherweight quarterfinals of the National AAU Tournament, losing by decision to Jerome Artis. It was his first defeat. Later that year, he boxed in the Eastern Olympic Trials. The rules stated that a boxer had to be seventeen to box in international competition, so Leonard, only sixteen, lied about his age. He made it to the lightweight semifinals, losing a disputed decision to Greg Whaley, who took such a beating that he wasn’t allowed to continue in the trials and never boxed again.

In 1973, Leonard won the National Golden Gloves Lightweight Championship, but lost to Randy Shields in the lightweight final of the National AAU Tournament. The following year, Leonard won the National Golden Gloves and National AAU Lightweight Championships. Leonard suffered his last two losses as an amateur in 1974. He lost a disputed decision to Anatoli Kamnev in Moscow, after which, Kamnev gave the winner’s trophy to Leonard. In Poland, Kazimierz Szczerba was given a decision victory over Leonard, even though he was dominated in the first two rounds and dropped three times in the third.

Leonard won the National Golden Gloves and National AAU Light Welterweight Championships in 1974. The following year, he again won the National AAU Light Welterweight Championship, as well as the Light Welterweight Championship at the Pan American Games.

In 1976, Leonard made the U.S. Olympic Team as the light welterweight representative. The team also included Leon and Michael Spinks, Howard Davis Jr., Leo Randolph, Charles Mooney, and John Tate. Many consider the 1976 U.S. team to be the greatest boxing team in the history of the Olympics. Leonard won his first four Olympic bouts by 5–0 decisions. He faced Kazimierz Szczerba in the semifinals and won by a 5–0 decision, avenging his last amateur loss.

Juanita Wilkinson, Leonard’s high school girlfriend, told him she was pregnant in the summer of 1973. They decided to have the baby but marriage would be put off until after the Olympics in 1976. Leonard would continue to pursue his Olympic dream while she and the baby, Ray Charles Leonard Jr., lived with her parents. When Leonard boxed in the Olympics, he had a picture of Wilkinson taped to his sock.

Leonard made his professional debut on February 5, 1977 before a crowd of 10,270 at the Civic Center in Baltimore. He was paid $40,044 for the fight. His opponent was Luis “The Bull” Vega, whom he defeated by a six-round unanimous decision. After the fight, Leonard paid back his $21,000 loan to the investors.

In his fourteenth professional fight, Leonard fought his first world-ranked opponent, Floyd Mayweather, who was ranked seventeenth. The fight took place on September 9, 1978. Leonard won by a tenth-round knockout. A month later, Leonard defeated his old amateur nemesis Randy Shields by a ten-round unanimous decision.

On August 12, 1979, Leonard knocked out Pete Ranzany in four rounds to win the NABF Welterweight Championship. The following month, he made his first title defense against Andy Price. Price, an up-and-coming contender who was sponsored by Marvin Gaye, had a reputation for prolonged bouts in earlier fights and was believed by sports reporters to defeat or give a long fight to Leonard. Although Price landed multiple good blows, Leonard knocked him out in the first round, advancing his record to 25–0 with 16 knockouts.

Leonard fought Wilfred Benítez for the WBC Welterweight Championship on November 30, 1979, at Caesar’s Palace in Las Vegas, Nevada. There was a capacity crowd of about 4,600. Leonard received $1 million and Benitez, a two-division champion with a record of 38–0–1, received $1.2 million.

Leonard made his first title defense in Landover, Maryland, on March 31, 1980. His opponent was Dave “Boy” Green. The British challenger had a record of 33–2. In the fourth round, Leonard knocked Green out with a devastating left hook. Leonard called it “the hardest single punch I ever threw.”

On June 20, 1980, Leonard returned to the Olympic Stadium in Montreal to defend his title against Roberto Durán before a crowd of 46,317. Durán, the former Undisputed World Lightweight Champion for 6 1/2 years, had a record of 71–1 and was the #1 welterweight contender and considered the best “Pound for Pound” fighter in the world. Durán received $1.5 million and Leonard, working for a percentage of the closed-circuit gate as well as a guarantee, received over $9 million.

Hearns, 32–0 with 30 knockouts, won the WBA Welterweight Championship in 1980, scoring a second-round knockout of José “Pipino” Cuevas in Detroit, Michigan. He made three successful title defenses, stopping Luis Primera, Randy Shields, and Pablo Baez.

Before the fight with Howard, Dave Jacobs rejoined Leonard’s team in a limited role. Jacobs had quit in 1980, disagreeing with Leonard’s decision to have an immediate rematch with Durán.

Leonard married his high school sweetheart, Juanita Wilkinson, in January 1980. Their six-year-old son, Ray Jr., served as the ring bearer. In 1984, they had another son, Jarrell. They were divorced in 1990. During divorce proceedings, Juanita Leonard testified that her husband physically abused her while under the influence of alcohol. She also said he was an occasional cocaine user. In his testimony, Leonard confirmed his wife’s claims and went on to reveal that the problems of their marriage were not due to drug and alcohol use.

On March 28, 1981, Leonard defended his title against Larry Bonds, the WBC sixth-ranked contender, at the Carrier Dome in Syracuse, New York. Bonds was a southpaw, which made him a good opponent for Leonard, given that his next opponent was scheduled to be the WBA Light Middleweight Champion Ayub Kalule, a southpaw.

Leonard moved up to the junior middleweight division and faced Kalule on June 25, 1981 at the Astrodome in Houston, Texas. Kalule, who was 36–0, had been the WBA Light Middleweight Champion for two years.

Promoted as “The Showdown”, Leonard fought Thomas Hearns on September 16, 1981 at Caesars Palace in Las Vegas to unify the World Welterweight Championship in a scheduled fifteen-rounder. They fought before a live crowd of 23,618. Hearns was paid $5.1 million, and Leonard made over $11 million. The fight grossed over $35 million. The live gate was $5.9 million, and the revenue from pay-per-view was $7.5 million.

On February 15, 1982, Leonard defended the unified title against Bruce Finch, the WBC fourth-ranked contender, in a bout at Reno, NV. Leonard knocked him out in the third round. Leonard’s next fight was scheduled to be against Roger Stafford on May 14, 1982, in Buffalo, New York. While training, Leonard started to see floaters. He went to a doctor and discovered that he had a detached retina. The fight was cancelled, and Leonard had surgery to repair the retina on May 9, 1982.

On November 9, 1982, Leonard invited Marvin Hagler and other boxing dignitaries to a charity event in Baltimore, Maryland to hear him announce whether he would continue his career. Standing in a boxing ring with Howard Cosell, the master of ceremonies, Leonard announced his retirement, saying a bout with Hagler would unfortunately never happen. Leonard maintained his eye was fully healed, but that he just didn’t want to box anymore.

After the Los Angeles Times broke the story, Leonard held a press conference and publicly acknowledged that the accusations were true. He said he started using after he retired in 1982, following surgery to repair a detached retina. “I wanted more”, Leonard said. “I wanted that arena. I didn’t want anyone to tell me my career had to end.” “I decided to search for a substitute…I resorted to cocaine. I used when I felt bad, I used when I missed competing at that level”, he said. “It was a crutch, something that enabled me to forget.” He said he quit using drugs in early 1986, when he woke up one morning and “what I saw in the mirror was scary.” “I can never erase the pain or the scars I have made through my stupidity, my selfishness”, Leonard said. “All I can do is say I’m sorry, but that is not enough.” In 2011, Leonard revealed in an NPR interview that he had been free of alcohol since July 2006.

Missing the limelight and the competition, Leonard announced in December 1983 that he was returning to the ring. Leonard boasted that he would have a couple of ten-round bouts and then take on Milton McCrory, Donald Curry, Durán, Hearns and finally Hagler. This decision was met with a torrent of criticism from fans and the media, who felt Leonard was taking unnecessary risks with his surgically repaired eye.

Leonard and Howard fought on May 11, 1984, in Worcester, Massachusetts. Howard knocked Leonard flat on his back in the fourth round. It was the first knockdown of Leonard’s professional career. Leonard came back to stop Howard in the ninth round, but the stoppage was disputed, with some feeling that the referee stopped the fight prematurely. Leonard was ahead on all three scorecards at the time of the stoppage. At the post-fight press conference, Leonard surprised everyone by announcing his retirement again, saying he just didn’t have it anymore.

On March 10, 1986, Marvin Hagler knocked out John Mugabi in eleven rounds to retain the Undisputed World Middleweight Championship for the twelfth time and advance his record to 62–2–2. “I was ringside”, Leonard said. “I’m watching John ‘The Beast’ Mugabi outbox Hagler. Of all people, John ‘The Beast’ Mugabi.” It was then that Leonard decided to come back and fight Hagler. He called Mike Trainer and said, “I can beat Hagler”.

On May 1, 1986, Leonard announced on a Washington, D.C. talk show that he would return to the ring to fight Hagler. The announcement generated a lot of controversy because of Leonard’s inactivity and eye injuries, yet it also excited many sports fans who had hoped to see them fight years earlier. Hagler took a few months to decide, then agreed to the match.

Despite requests from the Hagler camp, Leonard was uninterested in a rematch and retired on May 27, 1987. “I’ll try, I’ll give it a shot”, Leonard said of his latest retirement. “But you guys know me.” A month after Hagler’s formal retirement in June 1988, Leonard would announce another comeback.

On November 7, 1988, Leonard made another comeback, facing Donny Lalonde at Caesar’s Palace in Las Vegas. They fought for Lalonde’s WBC Light Heavyweight Championship and the newly created WBC Super Middleweight Championship, which meant that Lalonde had to make 168 lbs. Many were critical of the fact that Lalonde’s light heavyweight title was on the line when the weight limit of the fight with Leonard was at 168 pounds, and critical of Leonard for stipulating that his opponent—a natural 175 pounder—should weigh less than his usual fighting weight, which could possibly weaken him. However, Lalonde later told HBO’s Larry Merchant that he didn’t have any trouble making weight.

On June 12, 1989, Leonard defended the WBC Super Middleweight Championship in a rematch with Thomas Hearns at Caesar’s Palace. It was promoted as “The War.” Hearns was guaranteed $11 million and Leonard was guaranteed $14 million.

On December 7, 1989, Leonard defended the title against Roberto Durán, who was the reigning WBC Middleweight Champion. Durán was guaranteed $7.6 million and Leonard’s arrangement guaranteed him over $13 million.

In 1989, Leonard was introduced to Bernadette Robi by Kenny G at a Luther Vandross concert. Robi is the daughter of Paul Robi, one of the original Platters, and she is the ex-wife of Lynn Swann. Leonard and Robi were married at Leonard’s $8.7 million estate in Pacific Palisades, California in August 1993. At the wedding ceremony, the grounds were converted into a garden with 10,000 roses and blossoms of other flowers flown in from the Netherlands.

In January 1990, Leonard relinquished the WBC Super Middleweight Championship, saying that he was unsure whether he would fight again. When Leonard decided to continue his career, he offered Hagler a rematch, but Hagler decided to stay retired. He then offered Hearns a third fight, but Hearns said he could no longer make the weight and moved up to the light heavyweight division.

Leonard has worked as a boxing analyst for ABC, CBS, NBC, ESPN, HBO and EPIX. His relationship with HBO lasted for more than a decade. It ended in 1990, after HBO was not offered an opportunity to bid on the telecast rights to Leonard’s fight with Terry Norris. HBO believed it would be inappropriate for Leonard to continue with them if they couldn’t bid on his fights. Leonard’s attorney, Mike Trainer, said, “There never has been a linkage between his broadcasting and his fighting.”

On February 9, 1991, Leonard went down to 154 lbs and fought WBC Light Middleweight Champion Terry Norris at Madison Square Garden. Leonard entered the bout as a 3-1 favorite but Norris dominated the fight, giving Leonard a heavy beating. He knocked Leonard down with a left hook in the second round, and in the seventh, he dropped Leonard again with a short right. Leonard had no answer for the skillful, younger, faster man. Leonard went the distance but lost by a lopsided decision. The scores were 120–104, 119–103, and 116–110. After the verdict was announced, Leonard announced his retirement. “It took this fight to show me it is no longer my time”, Leonard said. “Tonight was my last fight. I know how Hagler felt now.”

In October 1996, the 40-year-old Leonard announced that he was coming out of retirement to fight 34-year-old Héctor Camacho for the lightly regarded International Boxing Council (IBC) Middleweight Championship. Camacho, a light-hitting southpaw, was a three-time world champion with a record of 62–3–1. However, Camacho was also considered to be past his prime. Leonard decided to fight Camacho after commentating on Camacho’s fight with the 45-year-old Roberto Durán the previous year, describing the disputed unanimous decision as “an early Christmas gift”.

In January 1997, it was announced that Leonard had been voted into the International Boxing Hall Of Fame in Canastota, New York. The rules state that a boxer must be retired for five years before being eligible for induction. When the vote took place, Leonard had been retired for more than five years, therefore, he was eligible, even though he had a fight scheduled. The induction ceremony was on June 15, 1997.

The fight with Camacho took place on March 1, 1997, in Atlantic City, New Jersey. Camacho applied pressure from the opening bell and started to score well in the third. He continued to score well in the fourth and opened a cut above Leonard’s right eye. In the fifth, Camacho dropped Leonard with a right followed by two left uppercuts. Leonard got up, but was unable to ward off Camacho. The referee stopped the fight with Camacho teeing off on a defenseless Leonard on the ropes. It was the only time in Leonard’s career that he was knocked out.

Leonard said he planned to have a series of tuneup fights before fighting a champion. He was scheduled to fight Tony Menefee on February 15, 1998, in Australia, but he pulled out of the fight, saying that he didn’t have the motivation. The Camacho fight was Leonard’s last. He finished his career with a record of 36–3–1 with 25 knockouts.

In 2001, Leonard launched Sugar Ray Leonard Boxing Inc., a boxing promotional company, and announced the company’s strategic partnership with ESPN. Together, Leonard and ESPN would produce and promote “Sugar Ray Leonard and ESPN II Presents Friday Night Fights”, which would air the first Friday of every month for twelve months. Leonard’s boxing promotional company was dissolved in 2004. He had a falling out with partner Bjorn Rebney, whom he called “a cancer in my company.” Speaking of his promotional company, Leonard said, “We did some great shows with evenly matched fights. I took great pride in it. But the TV show came about and made my decision a lot easier. I already had it in the back of my mind to dissolve the company. The working environment was not healthy.”

In 2007 he was awarded The Ambassador Award of Excellence by the LA Sports & Entertainment Commission at the Riviera Country Club for his continued community involvement.

Leonard testified before the Senate Committee on Homeland Security and Government Affairs in 2009. The Senate hearing was titled “Type 1 Diabetes Research: Real Progress and Real Hope for a Cure”. He testified about the burden of diabetes and the need for continued research funding to find a cure.

Leonard and his wife, Bernadette, founded the Sugar Ray Leonard Foundation to support the Juvenile Diabetes Research Foundation and its annual Walk for a Cure. In 2009, the foundation expanded to support programs that help people rebuild their communities in ten cities across the United States. It supports accessible housing, healthcare services, and educational services and job training.

Leonard has also worked as an actor. He has appeared in numerous television shows, including Half & Half, L.A. Heat, Married… with Children, Renegade and Tales From The Crypt. He has also appeared in several movies, including I Spy and most recently The Fighter (2010), starring Christian Bale and Mark Wahlberg. This movie brought back memories of his fight with Dicky Eklund. He also worked as an adviser in the 2011 robot boxing film Real Steel. Leonard served as host and mentor to the aspiring fighters on The Contender. Sylvester Stallone, who co-hosted during the first season, was one of the executive producers, along with Mark Burnett. When Leonard left the show, he was replaced as host by Tony Danza for the final season.

Leonard competed on season 12 of Dancing with the Stars, which premiered on Monday, March 21, 2011, on ABC. His partner was Anna Trebunskaya. He was voted off in Week 4 of the show. During his appearance on The Colbert Report in 2011, Leonard was defeated by host Stephen Colbert in a thumb wrestling contest. He appeared as a guest at the chef’s table, along with Tito Ortiz, during the tenth season of Hell’s Kitchen. He is the celebrity spokesperson for the Atlanta law firm John Foy and Associates, PC.

In his autobiography The Big Fight: My Life in and out of the Ring, published in June 2011, Leonard reveals that as a young boxer he was the victim of sexual abuse from an Olympic trainer as well as another man, a benefactor. He has since made public appearances to bring attention to the issue of child sex abuse, declaring himself a “poster child” for the cause and encouraging victims to report their abuse.