The singer and rapper joins The Stone Roses and recently confirmed acts Snow Patrol and Kasabian to headline the event, which runs from July 6-8.
Festival organisers are said to be "thrilled" with the last-minute booking, adding: "DF Concerts and founding partner Tennent's Lager are thrilled to announce that the feisty rapper has just been added to the stellar bill of names."
Tinie Tempah, New Order, David Guetta, Calvin Harris and Emeli Sandé are also among the latest crop of acts added to the festival's lineup.
Minaj was recently criticised by the Catholic League for her controversial performance at the Grammy Awards, which saw her being exorcised by a priest.
Her latest single, 'Starships', is on course to enter the top ten this Sunday.
Listen to 'Starships' below: