Mallett went 19-of-26 through the air, gaining 215 yards. Five completions went to D.J. Williams for 57 yards and two touchdowns for the 8-2 Razorbacks.
Mallett also found Chris Gragg, Cobi Hamilton and Jarius Wright on scoring strikes.
Arkansas benefited from 182 rushing yards and a touchdown by Knile Davis on 11 carries.
UTEP (6-5) lost for the fourth time in five games. Trevor Vittatoe was 13-of-21 passing for 151 yards and an interception.