The Fighting Sioux (4-2) trailed the NAIA school 3-0 after the first quarter, but took control after blocking a Bulldogs field-goal attempt. Miller, who finished with 152 yards in 20 carries, scored on runs of 3 and 2 yards, and Joey Bradley ran for a 3-yard touchdown in the second quarter to help North Dakota build a 21-6 lead at halftime.
Miller added scoring runs of 3 and 4 yards in the third quarter, and Bradley connected with R.J. McGill for a 13-yard score late in the third quarter to make it 42-6.
Zach McRae was 21 of 35 for 211 yards for Montana Western (1-5). He was intercepted twice.