Michael Herrick was 24 for 37 for 272 yards and one touchdown for the Lumberjacks (5-2, 4-1 Big Sky), who compiled 464 total yards, 33.5 more than their season average.
The Bengals (0-8, 0-5) have lost 20 straight on the road.
With NAU trailing 7-6, receiver Austin Shanks scored on a 24-yard reverse with just more than three minutes remaining in the opening quarter. Henderson then scored in the first minute of the second quarter, and the Lumberjacks built a 33-10 lead before halftime.
Herrick has now attempted 141 straight passes without throwing an interception.