Joanna Jedrzejczyk also retained her title
Stipe Miocic became only the fourth fighter in UFC history to defend the heavyweight title twice after a first round stoppage of Junior Dos Santos.
The champion absorbed a brutal early leg kick which left him limping but rallied to back the Brazilian against the cage and force a first-round stoppage.
With the victory, Miocic avenged his 2014 loss to Dos Santos and has now won his last five bouts by knock-out.
The co-main event saw the undefeated women's strawweight champion Joanna Jedrzejczyk defeat Jessica Andrade by unanimous decision.
The Polish fighter dominated her challenger to defend her belt for the fifth successive time.
That is one ferocious female fighter.— Conor McGregor (@TheNotoriousMMA) May 14, 2017
Lethal with every limb, and from every angle.
A truly amazing fighter.
"No one is taking this belt from me,” said the champion after the scores were read out, “no one.”
Damien Maia probably secured a welterweight title shot with a decision victory over Jorge Masvidal. Frankie Edgar put the breaks on the much vaunted Yair Rodriguez with an impressive second-round stoppage.
Elsewhere, there was controversy when the lightweight clash between former champion Eddie Alvarez and Dustin Poirier was stopped by the referee Herb Dean due to an accidental foul and ruled a no-contest.