The Tigers took a 28-23 lead into halftime before finding their collective shooting touch after the break.
TSU made 16 of 32 field goals and 6 of 12 3-point shots after halftime, pushing its lead to double digits with a 10-4 run to open the second half.
Alabama A&M (11-15, 8-8) pulled within 39-33 with 15 minutes left but would get no closer.
Texas Southern used an 18-5 run to open up a 70-49 lead with 2:58 left.
Arthur Capers lead AAMU, which shot 38.2 percent from the floor and 27.3 percent from deep, with 19 points.