The defender joined the Red Devils from Bayern Munich earlier this week and has been introduced into the side for the team's league opener against Marco Silva's team.
Mazraoui for Jonny Evans is the only change from the Community Shield, meaning that Mason Mount and Amad Diallo keep their spots in the side, with Bruno Fernandes set to play as the false nine.
Matthijs de Ligt and Joshua Zirkzee, who are also new signings at Old Trafford this summer, are both on the bench for the 20-time English champions tonight.
Alejandro Garnacho is also named among the substitutes, but there is no spot in the squad for Jadon Sancho amid the speculation surrounding his future.
As for Fulham, there is a debut for Emile Smith Rowe, who has arrived from Arsenal this summer.
Adama Traore is also included in a wide position, while there is a spot in the XI for former Man United attacker Andreas Pereira, who was linked with Chelsea earlier this summer.
Jorge Cuenca - another new signing - is on the bench, but Ryan Sessegnon misses out on the chance to make his second debut for the club due to an injury.
Manchester United: Onana; Dalot, Maguire, Martinez, Mazraoui; Casemiro, Mainoo; Amad, Mount, Rashford; Fernandes
Subs: Bayindir, De Ligt, Evans, Collyer, Eriksen, McTominay, Antony, Garnacho, Zirkzee
Fulham: Leno; Tete, Diop, Bassey, Robinson; Lukic, Pereira, Iwobi; Smith Rowe, Muniz, Traore
Subs: Benda, Castagne, Cuenca, Reed, Cairney, King, Wilson, Jimenez, Stansfield