Zavier Simpson supplied 12 points and Duncan Robinson scored all 11 points after halftime for the fifth-seeded Wolverines (25-7), who have won six straight. Moritz Wagner added 11 points before fouling out in regulation.
Michigan, which faces fourth-seeded Nebraska in the quarterfinals, has defeated Iowa in all six meetings in tournament history.
Ryan Kriener led the 12th-seeded Hawkeyes (14-19) with 14 points. Tyler Cook and Luke Garza contributed 13 points apiece and Jordan Bohannon chipped in 11 for Iowa.
Robinson made his third 3-pointer to give the Wolverines a 72-70 edge with 2:17 remaining in overtime. Simpson made two of four free throws during the next minute to make it a four-point game.
After Cook split a pair of free throws, both teams came up empty on their next two possessions. Robinson then hit two free throws with 10.1 seconds remaining and Bohannon missed a 3-point try. Matthews tacked on a free throw in the final second.
Garza scored 10 first-half points as the Hawkeyes led 40-35 at the break.
The Wolverines came out energized out of the locker room, scoring 11 unanswered points in 2:17 to take a 46-40 lead.
Bohannon ended Iowa's drought with a pair of free throws.
Kriener's three-point play with 9:52 left pulled Iowa within two points. Robinson ended the Wolverines' 3-point drought after 12 long-range misses on their next possession. Robinson soon popped open for another long ball to make it 59-51.
Nicholas Baer scored along the baseline to cut Iowa's deficit to 65-61 with 3:09 left. Matthews made a jumper a minute later. Baer answered with a 3-pointer.
Bohannon tied it at 67 with 16 seconds left after Muhammad-Ali Adbur-Rahkman missed the front end of a one-and-one. Abdur-Rahkman then missed a layup, forcing overtime.
Michigan swept the regular-season series, winning in Iowa City 75-68 on Jan. 2 and 74-59 in Ann Arbor.
--Field Level Media
Iowa | Michigan | |
Ryan Kriener 14 | Scoring | Charles Matthews 16 |
Jordan Bohannon 6 | Assists | Muhammad-Ali Abdur-Rahkman 3 |
Nicholas Baer 7 | Rebounds | Jon Teske 9 |
Jordan Bohannon 2 | Free Throws Made | Charles Matthews 6 |
Isaiah Moss 1 | Steals | Muhammad-Ali Abdur-Rahkman 2 |
Tyler Cook 1 | Blocks | Jon Teske 2 |