Craig Loston's interception stopped a potential game-tying drive, giving Hill a chance to put the game out of reach by carrying four times for 87 yards on a six-play, 92 yard march that gave the Tigers (10-3) a 21-7 lead.
Iowa (8-5) again pulled within a touchdown after Jordan Cotton returned the ensuing kickoff to the Tigers' 4.
Jennings rushed for a touchdown but only threw for 82 yards while standing in for the injured Zach Mettenberger in the freshman's first college start.
Backup quarterback C.J. Beathard 's fourth-down interception stopped one promising drive for Iowa, but he also tossed a 4-yard TD pass to Kevonte Martin-Manley to trim the Hawkeyes' deficit to 21-14 with 1:42 remaining.