The 27-year-old had gone into the clash hoping to usurp his heavyweight rival to become the poster boy of British boxing.
And Dubois rocked the world with a stunning performance, with the younger man ending the bout inside just five rounds.
Joshua was late arriving at Wembley, with the Watford-born star opting to warm up in his hotel room instead of turning up to watch the action on the undercard.
And that decision failed to pay off, with the heavyweight star second-best throughout the entirety of the clash.
Dubois was fast out of the blocks, producing thunderous power.
The 27-year-old was able to knock Joshua to the canvas inside the first round, with fans at Wembley left stunned by what they were seeing.
Joshua was second best in the second round, too, with the 34-year-old then floored once more in the third.