The 29-year-old Joshua has made six title defenses since first knocking out Charles Martin for the IBF title in 2016.
He went on to unify titles in wins over Wladimir Klitschko and Joseph Parker but has been heavily criticized in the U.S. for a lengthy 2018 negotiation with WBC champion Deontay Wilder (40-0-1, 39 KOs) that never came to fruition.
Wilder, 33, fought to a thrilling (and contested) spilt draw with unbeaten lineal champion Tyson Fury in December and the two appear headed toward a spring rematch.
Miller (23-0-1, 20 KOs) brings enough size at 6-foot-4, deceptive speed and volume punching to be an interesting opponent for the 6-foot-6 Joshua.
Although the fight will represent a considerable step up in competition for Miller, the former kick boxer has remained active of late and has stopped 11 of 12 opponents going back to 2015.
The brash Miller, a native of Brooklyn, New York, also brings a brash personality with him into the fight, which is one he has called for going back to 2017.
Miller crashed DAZN’s introductory news conference in New York last fall and needed to be held back from attacking Joshua.