World championship boxing returned to the historic Kensington venue for the first time in decades. Olympia had previously staged headline fights involving stars such as Chris Eubank Jr and Prince Naseem Hamed.
Harper strode towards the centre of the 19th-Century grand hall, buoyed by her travelling Yorkshire faithful.
Dubois, who once pretended to be a boy named Colin so she could be allowed to box, also received a warm reception as she entered to I’m Every Woman by Whitney Houston.
The fight had been a long time coming, and the rivalry had grown increasingly tense in the build-up. Dubois repeatedly questioned Harper’s achievements and credentials, while Harper shoved Dubois during a fiery media face-off earlier in the week.
By the halfway stage, however, the contest had not quite lived up to the hype, with Dubois edging the rounds through steady work to the body.
Then, suddenly, the fight came alive. Dubois set up a knockdown with a sharp double jab followed by a left hook, sending Harper to the canvas.
Harper rose to her feet as Dubois leapt in celebration, prompting the referee to warn her for failing to return to her corner.
Dubois increased the pressure. She landed thudding southpaw left hands in the seventh and eighth as blood began to drip from a cut on the inside of ‘Belter’ Harper’s left eye.
Watching from ringside was pound-for-pound star Claressa Shields.
A strong combination from Dubois in the ninth suggested a stoppage might be imminent, but Harper rallied to land shots to Dubois’ head in the 10th and final round.