The Yellow Jackets had a chance to tie but Zack Peacock's off-balance jumper at the buzzer never had a chance, falling short.
Ralph Mimms had given the Seminoles (11-4) a 64-63 lead with 35 seconds left on a jumper. The Yellow Jackets (6-6) tied it with 9.4 seconds left by D'Andre Bell, who made one of two free throws before Rich got the out of bounds pass in his end and dribbled the length of the floor for the game-winner.
Toney Douglas led Florida State with 22 points. Rich and Uche Echefu each had 11 and Mimms 10.
Anthony Morrow had 17 points for the Yellow Jackets and Bell added 15. Jeremis Smith had nine points and 11 rebounds.
Florida State, which hadn't played since a 101-95 loss at Providence on Dec. 22, led 40-34 at the half with Douglas scoring 13 points. It was tied at 32 when the Seminoles outscored Georgia Tech 8-2 in the final 3:41 with Douglas scoring five of those points.
Andre Bell had nine first-half points for the Yellow Jackets, who led 12-2 with only 2:28 gone in the game. The Seminoles got back in it and tied it at 19 midway in the period.
It was a battle of 3-point baskets before intermission with Florida State making 7-of-14 and Tech dropping in 6-of-12. In the Yellow Jackets previous game, an 83-73 win over Tennessee Tech on Friday night, they were only 2-of-11 on 3s. The Seminoles had a school record 20 in an 85-55 win over Maine on Dec. 8.
Florida State went 0-for-8 on 3s in the second half, finishing at 7-for-22. Tech was 2-for-6 and ended with 8-of-19.
The Seminoles Isaiah Swann, was 2-for-2 from the free throw line and has made 31 of 32 this season.
The last-second win deprived Georgia Tech coach Paul Hewitt of career victory 200. He is 199-28 overall in eight seasons with Tech and three with Sienna.