The victory ended the Aggies' (12-8, 4-5 Big 12) six-game losing streak to the Tigers.
Facing a 66-64 deficit with 2 1/2 minutes left, Texas A&M took the lead on a three-pointer by freshman Antoine Wright.
Missouri tied the game at 71-71 on Travon Bryant's three-pointer with 32 seconds left, but Jackson answered with a jumper from the right side of the lane.
The Tigers' inbounds pass was intercepted and A&M's two-game losing streak was over.
Arthur Johnson scored 18 points for the Tigers (14-6, 5-4), who fell to 2-5 on the road.