The 24-year-old British fighter extended his professional record to 18-1 - the only defeat of his career was against Joe Joyce in 2020 - with a clinical stoppage over home fancy Bryan to move a step closer to a shot at a major heavyweight title.
The Londoner is the mandatory challenger to the winner of Anthony Joshua's rematch with Oleksandr Usyk this summer.
"Now I can make some massive fights in the future," Dubois said. "I am so grateful for this moment.
"Bring them all on, I am ready."
'Dynamite' made light of the unusual surroundings of the quirky Casino Miami venue put up by promoter Don King to finish off his 32-year-old opponent with a punishing left hook and make it back-to-back wins in the States.
"I was just trying to figure him out in the first round," Dubois added on BT Sport. "I wanted to see what he had, I tested the chin and then went for it.
"It was a perfect ending and I am so happy. I think this will make me instantly a better fighter already."
Dubois' hopes of a potential blockbuster against countryman Joshua or Usyk is complicated by the fact that the winner of that rematch is likely to seek a unification fight.
Dubois said: "Thank you Mr King for setting me up for the big fights ahead. Maybe Dillian Whyte first if I have to wait for Joshua, Fury and Usyk."
Tyson Fury currently holds the WBC title but has said he intends to retire from boxing.
Dubois could instead defend the regular belt against the winner of the Hughie Fury vs Michael Hunter eliminator on July 2 in Manchester.