Merritt finished with 18 points and nine rebounds for the Bulldogs (11-16, 5-10 Southern Conference), who outscored Chattanooga 11-3 in the final 3:09 for their second win in three games.
The Mocs (13-15, 5-10) led 51-49 when Merritt hit a 3-pointer for a one-point lead with 3:09 remaining. Montgomery followed with another 3, and his free throw with 55 seconds left gave Samford a 56-51 advantage.
Samford hit 11 3-pointers and Chattanooga shot 25 percent from the free throw line (2-for-8).
Josh Davis added 16 points for the Bulldogs.
Taylor had 11 points and Sam Watson had 11 rebounds for the Mocs.