Ngannou weighed in at 255.5 pounds, while Dos Santos hit the scale at 249. The winner could be next in line for a heavyweight title shot.
The UFC Minneapolis main card will air on ESPN at 9 p.m. ET from Target Center (post show on ESPN+ at midnight).
Ngannou (13-3) has won two straight fights, most recently a 26-second knockout of Cain Velasquez at UFC Phoenix in February. The native of Cameroon by way of France has eight victories in the UFC, all by stoppage. Ngannou, 32, came up short in his first title attempt in 2018, losing by unanimous decision to Stipe Miocic.
Dos Santos (21-5) has won three in a row. The 35-year-old Brazilian finished Derrick Lewis by second-round TKO at UFC Wichita in March in his last bout. Dos Santos is a former UFC heavyweight champion and has been in five title fights.
The UFC Minneapolis flyweight contender co-main event is also official. Jussier Formiga hit the scale at 125.5 pounds, while Joseph Benavidez came in at 126. The winner has the inside track to be the next challenger for Henry Cejudo‘s 125-pound title, though the division is in flux.