Fight commentators were left disgusted by that the California State Athletic Commission allowed the fight to go ahead after the bout showed Robinson was clearly out of his depth.
Combat sports commentator Damon Martin described the knockout as "vicious".
Veteran boxing commentator Teddy Atlas could see the fight wasn't going to end well early in the contest.
"Robinson- Paul, this is not a fight, it's about to be goodnight, all Paul has to do is throw punch as Robinson comes," he posted on Twitter.
"I don't care about athletes or not, stop allowing guys who don't know how to fight into ring!! Paul has actually trained to fight. Awful.
"Sad. Dangerous. Again, why have a California Commission if they allow this?"
Paul continued to call out UFC superstar Conor McGregor after his win.