Mercer (4-4) led throughout after taking a 15-12 lead on Aaron's three-point play less than six minutes into the game, but the Wildcats (0-3) trailed by only 35-32 at halftime.
Florence's 3-pointer extended Mercer's lead to 50-43 with 12:51 to play. He hit another 3-pointer to make it 53-46 less than a minute later, and a third one to give the Bears a 60-48 lead at 9:51.
Fort Valley State never came closer than six points after that until the final 11 seconds, when Ray Northern's 3-pointer provided the game's final points.
Greg Sanders had 19 points and 10 rebounds for Fort Valley State.