Olympic champion Joshua won the title in only his 16th professional fight this month when he stopped American Charles Martin in the second round of their fight also at the O2.
"I can't tell you how excited I am to fight again, especially at the O2 which I have made my fortress," the 26-year-old Joshua said in a statement.
"My coaches have watched Breazeale for a long time and they knew he was going to be a player in the division and now we get the chance to go to war on June 25."
Like Joshua, the Californian Breazeale is also undefeated as a pro and appeared at the 2012 London Olympics, where Joshua won gold. His record is 17-0, with 15 wins inside the distance.
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Joshua's fellow Briton Tyson Fury holds the higher-profile WBA and WBO heavyweight belts after beating long-time champion Wladimir Klitschko in November.
Fury faces Klitschko in a re-match in Manchester on July 9.
"I am looking to get passed Breazeale in style and continue moving towards the unification fight everybody is waiting for," Joshua said of a possible match-up with Fury.
Fury, who was forced to vacate the IBF belt, stoked the fire recently when he described Joshua as a "pumped-up weightlifter".
(Reporting by Martyn Herman; Editing by Mark Heinrich)
