Iowa’s only other lead was 3-0 after their first drive of the first quarter.
Michael Myers was 4-5 in field goal attempts including a bomb from 50 yards out.
Bullock’s TD run was an unexpected 24 yard rush in the fourth quarter.
Northern Illinois quarterback Jordan Lynch scampered for over 100 yard on the day, frustrating the Iowa defense.
Northern Illinois got the ball back with 2:15 left to play. Lynch fumbled on the first play for a loss of two. A botched run play for 5 yards and missed screen pass brought up a 4th and 7. The Iowa defense chased Lunch from the pocket and forced an errant thrown into the turf to preserve the Iowa victory.
The win was Iowa’s 12th straight in a season-opener.
Iowa next faces Iowa State Saturday at home in Kinnick Stadium.