Joshua unified the WBA and IBF titles with his famous win over Wladimir Klitschko last April, before subsequently battling out a late stoppage win over Takam in Cardiff in October.
"He's a respectable competitor, he is the WBO heavyweight champion of the world, so it's like one step closer to adding a strap to my legacy".
"It's the first time in history that two reigning heavyweight World champions have met in Britain and it's a classic match-up between two young, fast, undefeated belt holders and it's going to be an explosive fight".
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Joshua, 28, holds the IBF and WBA belts, while New Zealander Parker is the WBO champion.
Parker's camp have been pushing for the fight ever since Joshua defeated Takam a year ago.
"This is another huge unification fight for Anthony as he continues to make history in the quest to become undisputed world heavyweight champion".
Joshua's promoters Matchroom Boxing confirmed the deal on Sunday, concluding weeks of fractious negotiations between the two sides. My promoters are focused on what they have to do and I know what I have to do - train hard, be mentally strong, be in great shape and put in a great performance. He's consistently fought fighters in the world's top ten and he's beaten them all easily. "It certainly won't be a shock to me when he beats Anthony Joshua and takes his titles back home to New Zealand".
"Inside the stadium, boxing fans can expect yet another spectacular arena transformation, just days after the NatWest 6 Nations and ahead of Judgement Day VI and four nights of Ed Sheeran and more".
An announcement on on-sale dates, ticket prices and travel packages will be made soon.