The Sooners went down in order in the first, but they got something going in the top of the second when pitcher Keilani Ricketts and first baseman Chana'e Jones recorded back-to-back walks.
However, catcher Dani Dobbs flew out, Mizzou got a 3-6 fielder's choice and designated player Jessica Shults struck out swinging, ending the threat.
The Tigers built off that momentum in the bottom half, as they plated the first run of the game on a throwing error by Dobbs.
They added another run in the fourth when designated player Catherine Lee came home, thanks to another Sooner error, this time by second baseman Brianna Turang.
OU's gift giving continued in the bottom of the sixth when MU scored two more on a pair of errors.
Shortstop Javen Henson's throw was errant, allowing third baseman Nicole Hudson and first baseman Ashley Fleming to cross the plate for the Tigers.
Those proved to be a pair of critical insurance runs, as Dobbs homered to lead off the seventh, and left fielder Brittany Williams reached in what would have been the tying run had OU held serve in the previous inning.
After a lineout double play from pinch hitter Katie Norris, two more Sooners singled, but Turang popped up to end it.
Ricketts faced 26 batters and gave up an earned run on six hits and a walk, while striking out five in a losing decision.
Mizzou's Chelsea Thomas also allowed one earned run and equally as many hits, while walking two and striking out six of her 29 batters faced.
The Sooners finish the season 43-19.