WBC champion

At age 24, on February 3, 2007, Dawson won the WBC light heavyweight title against the undefeated, top-ten ranked champion Tomasz Adamek. The judges gave Dawson a unanimous decision victory, with scores of 118–108, 117–109, and 116–110.^[7] In June 2007, Dawson defended the WBC title for the first time, in a fight with Jesus Ruiz (19–5–0), winning by technical knockout in round six. The fight was broadcast on Showtime as part of a card that featured former light heavyweight champion Antonio Tarver. On September 29, 2007, Dawson defeated Epifanio Mendoza by fourth-round TKO in his second title defense. In April 2008 as his third title defense, Dawson retained the belt by a controversial unanimous decision victory against challenger Glen Johnson. The three judges each had the fight scored 116–112 in favor of the champion Dawson.^[8] Again aired on Showtime, for Dawson the card marked the second occasion for which he and Tarver fought in separate bouts on the same card, with Tarver winning each featured bout.^[9]

Dawson then vacated the WBC title in mid-2008.

Dawson, who is married and has three sons,^[10] still lives and trains in New Haven, Connecticut. His trainer is "Iceman" John Scully.^[11] He was formerly trained by Dan Birmingham, Floyd Mayweather Sr. and Eddie Mustafa Muhammad.

On October 11, 2008, at the Palms Casino in Las Vegas, Dawson fought IBF light heavyweight title holder Antonio Tarver. Dawson, who controlled the pace and landed most of the significant punches for a majority of the fight, was more active in methodically wearing out his opponent. Tarver landed the occasional punch, but Dawson was in control for most of the fight. With 2:11 left in the final round, Dawson scored a knockdown against Tarver, the only knockdown in the fight. Dawson won the fight by unanimous decision with scores of 117–110 from two judges and 118–109 from the third judge.^[12] Dawson earned $800,000 for the fight and Tarver earned $1 million.^[13]

On November 9, the day after Joe Calzaghe's win over Roy Jones Jr., Dawson issued a press release challenging Calzaghe and offered to fight him on his home turf in Wales. Dawson stated "I'm ready to give Joe the opportunity to draw the curtain on his great career in front of his family and friends and 70,000 fans," and "It's the best fight in the light heavyweight division between two undefeated champions." Calzaghe was to retire weeks later, as had been expected prior to the Jones Jr bout. Dawson himself was complimentary about the departing Welsh champion, stating "I applaud Joe's decision. It's obvious he and his family gave it a lot of thought. Timing is everything, and to leave center stage at his peak is rare and certainly comparable to the retirements of Rocky Marciano and Jim Brown."^[14]

Seven months after their first fight, Dawson and Tarver fought a rematch on May 9, 2009, in Las Vegas. The fight was similar to their first, with Dawson in control most of the fight, outworking Tarver much of the fight, and earning another unanimous decision win. The judges scorecards were 117–111, 117–111 and 116–112, all in favor of Dawson.

On May 27, 2009, Dawson vacated the IBF light heavyweight title to negotiate a rematch with Glen Johnson.^[15] On November 7, 2009, Dawson once again outpointed Glen Johnson. This time was more convincing but the judges scored it 117–111, 115–113 and 115–113 all for Dawson.^[16]

First defeat against Pascal

The next step in Dawson's career was a shot to regain the WBC title against Top 10 light heavyweight Jean Pascal on August 14, 2010, in Montreal and was for The Ring light heavyweight title.^[17] Pascal won the fight by technical decision in round 11 after an accidental head butt. All three judges had Pascal winning by a considerably wide margin at the time of the stoppage.

Dawson returned to action on May 21, 2011, against Adrian Diaconu and defeated Diaconu by unanimous decision. His first bout under the guidance of Emanuel Steward.

Dawson vs. Hopkins I, II

Dawson initially won The Ring, WBC and lineal light heavyweight titles due to a controversial TKO win, when Hopkins was unable to continue after getting thrown from a clinch.^[18] However, on October 20, 2011, the TKO ruling was ruled a Technical Draw by the WBC and Hopkins remained the champion.^[19] On December 13, 2011, the California State Athletic Commission changed the official decision to a No Contest (NC). Two days later, the WBC ordered a rematch between Hopkins and Dawson.

Dawson and Bernard Hopkins met again on April 28, 2012, at Boardwalk Hall in Atlantic City.^[20] The fight was slow-paced, with Dawson controlling most of the action and pace of the fight. Hopkins would throw and land an occasional punch, but Dawson would land the harder and more effective punches and outwork Hopkins for much of the fight. Noteworthy to mention is a period after a middle round where his trainer, former contender Iceman John Scully, caught Dawson mentally slipping and motivated him back into focus. The key moment in the fight was noted during the broadcast by HBO's Emanuel Steward and Jim Lampley. Dawson went on to win the fight by majority decision, with the judges scorecards reading 114–114, 117–111 and 117–111.

Compubox had Dawson outlanding Hopkins throughout the fight. Dawson landed 151 of 431 (35%) of his total punches, to Hopkins' landing 106 of 400 (26%) of his. Dawson said after the fight he is very interested in fighting WBC super middleweight champion Andre Ward, as well as fighting in a rematch with Jean Pascal.

Dawson vs. Ward

On September 8, 2012, Dawson stepped down a weight division (a rarity in the sport) to take on WBA, WBC, The Ring and lineal super middleweight champion, Super Six World Boxing Classic winner and one of the universally recognized top pound-for-pound fighters in the world Andre Ward.

Reports surfaced that Dawson was knocked out by Edison Miranda in sparring for the Ward fight.^[21] The fight started quite cagey with both fighters feeling each other out and only exchanging single shots, with Dawson landing his jab on Ward comfortably. In the 3rd round, a clash of heads changed the entire landscape of the fight in Ward's favour, as he seemed to have found out his opponent and proceeded to catch Dawson with some telling shots, dropping him to one knee with a right to the body and short overhand left hook. Dawson quickly rose to an 8-count and appeared to be dazed but managed to see out the round and return to his corner. In round 4, Ward showed no sign of letting up, upping the tempo and again catching a sluggish Dawson with a close left hook, again causing him to drop to his knee and the ref gave Dawson another 8 count. Dawson showed great resilience to see out the round and went on for the next 4 rounds avoiding Wards' troublesome left hooks with little activity himself. In round 10, it all came to an end as Dawson looked to have tired from Wards' consistent battery and possibly because of the weight loss also, he was caught flush with 4 shots in a row appearing to voluntarily take a knee. The referee stepped in asking Dawson if he wanted the fight stopped, Dawson did not speak but had the body language of a defeated man. The fight was called off and Ward retained his titles.

Dawson vs. Stevenson

On June 8, 2013, after his loss to Ward, Dawson returned to light heavyweight and defended his WBC, lineal, and The Ring titles against Haitian-Canadian Adonis Stevenson, a super middleweight contender who was fighting his first match at light heavyweight. The fight took place in Montreal, Stevenson's adopted hometown and where Dawson was fighting for the third time in the past two years.

Although Dawson entered the fight as a favorite, many were worried that draining himself to fight Ward, and the Ward fight itself had taken something from Dawson. Early in the fight he was caught with a hard left hook and fell backwards to the canvas. Although he got up from the punch and rose before the count of eight, the referee noticed that Dawson's legs were unsteady and stopped the fight at 1:11 of the first round despite the protests of Dawson and his trainer Eddie Mustafa Muhammad. It was the first time in Dawson's career that he had been knocked out in the first round.

Return to the ring

After taking the rest of 2013 off Dawson accepted a fight with journeyman George Blades, which was televised as part of the preliminary bout undercard of a Showtime event on June 14, 2014. The fight was fought in the cruiserweight division, at a catchweight of 179 pounds. Dawson failed to make weight for the contest, weighing in at 182.8 pounds, and thus had to forfeit one-fifth of his $15,000 purse.

Dawson knocked Blades out in the first round after dropping him twice. After the fight he said he wanted to start competing for a world title again and would be fighting at light heavyweight.

However Dawson's career took another hit when on October 4, 2014, he lost a split decision to Tommy Karpency. Dawson looked listless in the fight, displaying little of his once vaunted athleticism. After the fight Dawson maintained that he injured his left hand in the third round, stating that it prevented him from throwing combinations.