The Bracken light heavyweight took on Finland’s Krenar Aliu, a recent European Youth bronze medalist, in the Last 16, and scored a destructive points victory.
Giving away a big height advantage, O’Reilly’s long lead left hook caused some damage in the first, forcing the Nordic boxer to the ropes and rocking his head back.
O’Reilly’s power was making a dent, and Aliu’s output notably slowed in the second stanza as the Balbriggan boxer continued to force his man back with big, hurtful shots.
Both tired by the third, it was a scrappy round, but it was the Dubliner who was looking to press the action as the bout drew to a conclusion.
O’Reilly will now fight to guarantee a bronze medal on Wednesday morning against Kazakh Bekzad Nurdaueltov.
Earlier in the day there was a sensational victory for Gabriel Dossen, while Jordan Moore bowed out.