Ukrainian pound-for-pound superstar Vasyl Lomachenko was forced to produce a battling display to overcome Luke Campbell on points and add the WBC lightweight title to his WBA and WBO belts.
The 31-year-old three-weight world champion, already regarded as one of the best boxers in history, was made to work hard for the thrilling win.
Campbell, also 31, was aiming to become a world champion for the first time in his pro career, but was floored in the 11th as the Ukrainian's class proved decisive.
Lomachenko got the verdict 119-108, 119-108, 118-108 at London's O2 Arena.
Campbell, an Olympic gold medallist in 2012, suffered the third loss of his 23-fight professional career but was deserving of praise for the way he fought back to hear the final bell.
"He is so good, he adapts to any plans," said Campbell. "Tonight was not the jackpot but my time will come."
The Hull hitter was in trouble at the end of the fifth when he was caught by a crushing left hook from the double Olympic champion, but weathered an ensuing barrage of body and head shots to be saved by the bell.
Campbell took more of the same punishment in the sixth stanza, but had success of his own later on in the same round and continued the rhythm into the next segment in a captivating contest.
But then disaster struck as he was floored in the 11th after a bombardment of body shots, culminating in a hard jab. But he bravely got up to finish the fight in front of a lively, sold-out O2 crowd, although two of the three judges did not give him a round on their scorecards, only a share of one.
Campbell was later taken to hospital but promoter Eddie Hearn said it was only a precautionary measure.
The filled crowd at the O2 Arena paid witnessed to fantastic, dominant performance from the magician Lomachenko, a history-making world champion who finished the most successful amateur career ever at an astonishing 396-1.
This latest victory - in only his 15th fight as a professional - means he now holds three of the main four belts in the lightweight division - Ghana's Richard Commey, the IBF champion, is the man standing between him and being undisputed champion.
Lomachenko has also held world titles at featherweight and super-featherweight and fought for a world title in his second professional contest following on from an incredible amateur career that saw him win seven gold medals in major tournaments.
Less than five miles away from where he won his second gold medal at London 2012 Olympics - the first gold medal being in Beijing 2008 - and in his first professional fight in Europe, 'Hi-Tech' dazzled from the opening bell.
Before the fight, promoter Hearn said it was an "honour" to habe the Ukrainian fighting in the UK - and he did not disappoint the expectant onlookers.
The right jab from his southpaw stance proved a constant menace and the left was incredibly dangerous, twice rocking Campbell's head back as early as the third round.
He also provided some brutal body shots, leaving Campbell wincing in pain in the fourth.
Lomachenko was respectful towards his opponent before and after the contest as he told BBC Radio 5 Live: "He has big amateur experience, he's a smart fighter, a technical fighter and you saw his reach so of course it was hard for me.
"He gave me a good experience and a good fight. I want a unification fight for the four belts."
Campbell left the ring with his head held high as the Hull man hung un to the final bell under duress but also had many moments of success despite the officials not giving him a clear round on the cards.
In the build-up to this fight, legendary promoter Bob Arum said Lomachenko was the greatest technical fighter in boxing since Muhammad Ali and also compared him to other greats including Marvin Hagler, Sugar Ray Leonard, Floyd Mayweather, Oscar de la Hoya and Manny Pacquiao after the fight had finished.
Lasting the distance against a once in a geneation great shows just what a brave and gutsy effort it was from Campbell.
This was his second world title shot after he lost on a controversial split decision against Jorge Linares in the US in September 2017.
On that occasion, Campbell, whose father died two weeks before the fight, was knocked down in the second round but rallied back and later insisted he won the fight by a two-round margin in what was an enthralling, close contest against the Venezuelan stylist, who also lost to Lomachenko in his career but scored a knockdown against him.
Campbell, a 10-1 underdog, did not look like hw would get close to gaining the victory, as the Ukrainian was too good, despite the Briton being two inches taller and having a substantial five-inch reach advantage.
Lomachenko was fighting a British opponent for only the second time, after knocking out former world champion Anthony Crolla in the fourth round in the US earlier this year.
Campbell managed to go the distance, but a shock win was not to happen.
Former world champion Carl Frampton reacted to the gritty performance, "I never expected that. It was down to Luke Campbell who showed such skill alongside grit and determination. His stock has risen dramatically tonight even though he is the loser. I think Lomachenko underplayed how hard that was. I think it's the toughest fight he has had as a professional."
BBC Sport boxing correspondent Mike Costello also commented, "Three of the four versions of the title now rest with Vasyl Lomachenko. But people who haven't seen it won't realise how hard he has had to work for it."
Steve Bunce added, "We came for sorcery and were given a display of old-fashioned grit, determination and heart and desire. Such bravery, such guts. The points mean nothing. Luke Campbell made the magician look normal."
Defending WBC flyweight champion, Charlie Edwards (15-1, 6 KOs), retained his championship in underwhelming fashion after the fight with WBC #1 Julio Cesar Martinez (14-1, 11 KOs) was declared a “No Contest”, after a third-round saw the mandatory challenger from Mexico follow up with an illegal liver punch when the champion was already on his knees.
Edwards could not beat the count of 10 and Martinez was momentarily declared the new champion, but the WBC immediately decreed the fight as a “No Contest” and ordered a direct rematch.