The card goes down August 3 from Brazil’s HSBC Arena in Rio de Janeiro.
McCall (11-4-1) is 0-2-1 in his three UFC appearances, including a loss to current division champion Demetrious Johnson. He was one of four selected for the first-ever UFC flyweight title tournament.
Santos (27-7) had his six-fight win streak snapped by Yuri Alcantara earlier this year in his Octagon debut.
The main event boasts Jose Aldo putting his UFC featherweight title on the line against Anthony Pettis.