Holding No. 11 Georgia to 18.2 percent shooting, MSU led from start to finish in pulling a 50-38 Southeastern Conference upset in the Humphrey Coliseum.
"What a way to send Darriel out on a high note," MSU head coach Vic Schaefer said. "I am so proud of these players and coaches. You could see the flame of the Lord through them tonight. That was an incredible effort. To know how hard these players have worked and how much adversity they have had to overcome, I could not be more proud to be their coach."
Playing in front of her family, Gaynor sparked MSU with 11 points. Sophomore Kendra Grant scored 13 points, and Martha Alwal recorded her 15th double-double with 12 points and 14 rebounds.
"It means everything to me. This year alone has been record-breaking," Gaynor said. "Since I've been here, we've never beaten Arkansas, never beaten Missouri and never won on senior night. I'm so happy and so proud of my team. They did this for me. The whole time they kept telling me to keep shooting and kept encouraging me. This is my No. 1 memory from Mississippi State."
MSU knocked off Georgia for an eighth time in the Humphrey Coliseum. The home-standing Bulldogs snapped a three-game losing streak in the series. MSU knocked off a ranked opponent for the first time since defeating eighth-ranked Ohio State in the 2010 NCAA tournament.
The Maroon and White defense held Georgia to the lowest point total in the 39 games between lone pair of Bulldogs in the league.
With the victory, MSU improved to 13-15 overall and 5-10 in league play, while Georgia fell to 23-5 and 11-4.
"We held Georgia to five field goals in the second half," Schaefer said. "Think about that. That is what I am all about. I want to play the type of defense that you have to bleed to score. We held the No. 11 team in the nation to 18 percent shooting and five field goals in the second half.
"With the game on the line in the second half, we got stop after stop after stop."
MSU started on the attack from the opening tip. The Maroon and White scored the game's first 10 points as 3-pointer by Grant gave MSU a 10-0 advantage with 17:25 left before halftime.
The Maroon and White kept the early pressure going and stretched the lead to 24-9 on an Alwal jumper with 7:43 left. From there, MSU did not score the rest of the way and Georgia drew within 24-22 at halftime.
"We wanted to come out and throw the first punch," Schaefer said. "Martha was really a monster there in the first half, especially the first 10 minutes. We don't win the game without her playing that way. We knew Georgia would make a run. A well-coached team with good players will do that.
"To be able to stop their run and hold on says a lot about this team."
MSU built a 27-22 lead early in the second half on a 3-point play by Carnecia Williams. The lead was pushed back to eight at 33-25 on a Jerica James 3-point basket with 13:54 left.
Georgia closed within 35-33 but could never get on the hump. UGA was held to two field goals over the final 6:27. James hit a key 3-point basket for a 38-33 lead and the home team hit free throws the rest of the way to close out the win.
For the contest, MSU hit 15 of 48 shots from the field (31.3 percent), 6 of 18 shots from 3-point range (33.3 percent) and 14 of 17 shots from the free throw line (82.4 percent). Georgia hit 10 of 55 shots from the field (18.2 percent), 2 of 22 shots from 3-point range (9.1 percent) and 16 of 24 shots from the foul line (66.7 percent).
The teams were even at 42 in rebounds. MSU had nine assists and 18 turnovers, while Georgia had four assists and 16 turnovers.
Anne Marie Armstrong posted a double-double for Georgia with 10 points and 10 rebounds. Jasmine Hassell also pulled down a game-high 12 rebounds.
MSU closes the regular season with a 2 p.m. start Sunday at Auburn.