Jackson had six assists in the blowout and Will Barton posted a double-double of 18 points and 13 rebounds for Memphis (26-8).
DeAndre Kane led Marshall (21-13) with 16 points and Damier Pitts scored 12. The Thundering Herd came into the tournament seeded No. 6 and knocked off second-seed Southern Mississippi and third-seeded Tulsa en route to the finals.
The Tigers shot 59.1 percent from the field Saturday while Marshall struggled at 35.5 percent and a meek 8-of-18 from the free throw line. Memphis led 45-27 at the half.