More than 73,000 people were in attendance for the highly-anticipated fight, which began with Saunders exploding out of the blocks with a ton of energy, but failing to land a scoring shot.
After Saunders’ early burst, Alvarez took control of the ring to trap the Englishman in the corner and sneak in multiple shots to the body.
Alvarez maintained the advantage throughout the early rounds, but was unable to deliver a decisive blow.
The momentum briefly switched in the fifth round when Saunders stunned the Mexican with a strong left hook.
However, Alvarez quickly regained his composure, outworking his opponent until he landed a flurry of head punches in the eighth round which opened up a cut below Saunders’s right eye.
The Briton’s corner ultimately called an end to the bout while treating the eye in between the eighth and ninth rounds.
“He couldn’t see,” said Eddie Hearn, Saunders’ promoter. “I spoke with (trainer) Mark Tibbs and he wouldn’t let him go out. I thought he boxed beautifully. Canelo took his time, Billy is so tricky, but Canelo busted him up.”
Following the TKO victory, Alvarez now holds hold three of the four belts in the 168lb division having added the WBO super middleweight championship to his collection.
“I knew the fight was going to develop around the eighth round,” said Alvarez, whose only defeat was to Floyd Mayweather Jr in 2013. “It wasn’t as difficult as I expected. I know my preparation is good and I improve day-by-day.”