Adesanya ranks No. 3 overall in UFC's pound-for-pound rankings and has held the middleweight title since April 2019 with one unification bout victory and two successful defenses.
UFC 259 is scheduled for March 6. The location is to be determined.
Blachowicz is No. 15 in UFC's pound-for-pound rankings but has an impressive resume himself.
He won the light heavyweight title with a technical knockout over Dominick Reyes at UFC 253 last September. That punctuated a four-bout win streak that cemented him as a legitimate threat in the division. Now Blachowicz (27-8, 8 KOs) will make his first title defense against one of the sport's superstars in Adesanya.
The Nigerian is 20-0 with 15 knockouts and at the top of his game, taking down Robert Whittaker, Yoel Romero, Anderson Silva, Derek Brunson and Kelvin Gastelum in recent events. This will also be his first bout since September when he defeated Paulo Costa in his second title defense since unifying the middleweight belt.
Adesanya could be on the verge of holding two belts at once and cementing his status as one of MMA's most fearsome fighters.