Williams, a junior, and Walker, a senior, captured the title over the second-seeded team from North Texas by winning a tiebreaker in the final.
The Abilene Christian duo rallied from a 7-4 deficit in the game score to force the tiebreak. There, Williams and Walker came back from a 5-2 hole to win six of the next seven points and prevail 8-6.
It marked the first Midland championship by Abilene Christian since 2010.
In reaching the finals, sixth-seeded Williams and Walker survived a grueling stretch of matches against high-profile teams.
They beat unseeded North Texas 8-2 in the first round and then doubled up Nebraska 8-4 to reach the quarterfinals. That win was followed by another triumph over the Cornhuskers, this time beating the third seeds 8-3.
In the semifinals, Williams and Walker scored a giant 8-4 upset of the top-seeded team from Texas Tech.