CONOR McGregor has become the first fighter in UFC history to hold titles in two divisions simultaneously after a stunning KO of Eddie Alvarez in New York.

The Irish megastar knocked out Alvarez early in the second round at UFC 205 on Sunday (AEDT) to add the lightweight title to the featherweight belt he snared from Jose Aldo in 13 seconds.

McGregor almost put the fight away in the first round after landing a vicious left hook similar to that of the one which destroyed Aldo.

After dominating the first round, McGregor began to showboat before ending the fight.

With Alvarez charging forward, McGregor slipped the punch and replied with a left, right, left and right which sent the New Yorker to the canvas.

WATCH McGREGOR KO ALVAREZ IN THE VIDEO PLAYER ABOVE

MCGREGOR’S ASTONISHING CAREER FEATS

THE RUSSIAN MONSTER WHO WANTS A CRACK AT ‘CHICKEN’ MCGREGOR

FLYING KNEE ENDS IN UFC 205 BLOODBATH

Conor McGregor thanks Eddie Alvarez for the fight. Source: FOX SPORTS

Referee John McCarthy had no choice but to stop the fight with McGregor victorious three minutes and four seconds into the second round.

“I’ve ridiculed everyone on the roster,” McGregor said after the match.

“I’d like to take this chance to apologise to nobody. The double champ does what he wants.”

“... What’s next for me? The easy answer: Whatever the “Notorious” one wants.

McGregor dominated from the opening bell of the biggest card in UFC history — on pace to set an MMA pay-per-view record — and the sold-out crowd of 20,427 loaded with A-listers from Madonna to Hugh Jackman went wild with each punishing blow.

Unlike UFC’s laborious legal battle to reach New York, McGregor wouldn’t make anyone wait.

UFC has not decided if McGregor (21-3) will be allowed to defend both championships. UFC President Dana White said McGregor could be about the only fighter in the promotion to handle that kind of grueling fight load.

“Who knows,” White said. “I’m going to let him enjoy his night.”

Earlier on the card, Tyron Woodley reclaimed his welterweight belt in controversial fashion, keeping the title after a majority draw with Stephen Thompson.

Woodley was initially announced as the winner of the fight, before officials corrected the decision.

Tyron Woodley of the United States (left) fights against Stephen Thompson of the United States. Source: Getty Images

Polish superstar Joanna Jedrzejczyk reclaimed the strawweight belt, but not before surviving the battle of her career so far in a unanimous decision win over countrywoman Karolina Kowalkiewicz.

Yoel Romero beat Chris Weidman with a flying knee knockout to become the No.1 contender for Michael Bisping’s middleweight title.

In the first event of the main card, former women’s bantamweight champion Miesha Tate announced her retirement just moments after a unanimous decision defeat to Raquel Pennington.

Tate, 30, took the title from Holly Holm before losing it to Amanda Nunes in July.

“It’s because of the result,” Tate said after the loss.

“I felt like I had more to give but I just couldn’t get it done.”

REPORT CARD: ‘I’D LIKE TO APOLOGISE FOR ABSOLUTELY NOTHING’

BELT DRAMA: MOVE THAT SHOWS WHAT UFC WILL DO FOR MCGREGOR

During the prelims, Khabib Nurmagomedov wasted little time trying to line up McGregor’s next fight by calling out the Irishman after he his third round submission win over Michael Johnson.

“I want to fight your chicken,” Nurmagomedov told the crowd after his match.

Nurmagomedov said he believes he’s next in line for a shot at the lightweight title.

In the last of the prelims, Frankie Edgar beat Jeremy Stephens by unanimous decision in their featherweight match.

Re-live the action in our blog below: