Zach Davis walked to lead off the bottom of the ninth.
Davis, who leads the Big 12 in stolen bases, advanced to second on a balk before Tyler Neslony singled to right field.
That put Davis 90 feet away from home plate before the Gutierrez was intentionally walked to load the bases.
Hunter Hargrove then stepped to the plate and delivered the walk-off single to deep left field to give Texas Tech the 5-4 victory over ACU Wednesday night at Security Bank Ballpark in Midland.
Hargrove and Neslony led the way offensive for Texas Tech with two hits each.