Wilder wasted no time in unloading on his fellow American, throwing power punches from the outset.
The WBC champion landed a strong right hand after less than a minute to push Breazeale back into the corner.
However, on his way in to charge down the challenger, he was caught by a flush right hand from Breazeale and looked uncomfortable.
After clinching briefly and holding on, the referee split the fighters apart, and when they were brought together again, Deontay Wilder unleashed a horrible right hand on Breazeale’s chin, catching him flush.
Breazeale was left on his back on the canvas, before rising to his feet on the ninth of ten seconds in the count.
The fight was ended with just less than a minute remaining of the first round, meaning Wilder’s ring walk officially lasted longer than the fight.
Wilder wore a bizarre Game of Thrones-inspired ensemble for his ring walk, and was flanked by a group of performers.
Boxing fans immediately took to the internet after the fight to praise the champion, whilst some criticised Breazeale.
One fan even defaced Breazeale’s Wikipedia page, adding: “Dominic Breazeale killed on May 18 2019 after Deontay Wilder “Debo-ed” him.” to the introduction.
Other fans tweeted their admiration for Wilder’s knockout ability, and called for him to face Anthony Joshua next.
One fan posted: “That has to be the sweetest KO ever. The noise.”
“Wilder is a monster. Boxing at its finest,” another wrote.
“Anthony Joshua is not beating Wilder dawg lol,” another posted.
One fan joked: “This is why Joshua doesn’t want that smoke with Wilder.”
Another wrote: “Anthony Joshua wants no piece of Wilder after this fight lmao.”