Guy scored 18 points in the first half, when he made as many field goals as the Seminoles, and Key added 12 before the break.
Kyle Guy scored a game-high 21-points against FSU.
Florida State will return home and look to regroup against Miami on Wednesday (9 p.m., RSN) before facing perhaps an even bigger challenge in the form of No. 1 Duke on Saturday.
Florida State: The Seminoles came in having scored 73 or more points in all but two games and 80 or more in all but four.
"We were locked in and were ready to play defensively", Bennett said.
It was the fourth 20-point performance of Key's collegiate career, with the three other times coming in a Crimson Tide jersey.
"The fans were great, I think they've been great all season", said Key, who is shooting a combined 13 for 18 (72 percent) from the field over his last three games.
"He let the game come to him and made some shots when they were there, attacked when it was there", Virginia coach Tony Bennett said of the transfer from Alabama.
Sophomore guard De'Andre Hunter says, "He works his butt off in practice, and after practice".
Junior forward Mamadi Diakite adds, "He actually gives me a lot of hard times in practice". Hunter, who also pulled down six boards Saturday, said he wasn't a bit surprised by Key's offensive production, especially on a team with so many weapons. It was the first game all season that he had not started.
The junior is hitting 48-percent of his shots from behind the line.
The victory was one of 29 in a row for the Seminoles that included three ACC titles as well as the final crystal football to be awarded - and clearly showed the world that the best team to play the game may just have originated in Tallahassee. PJ Savoy had 8 points and M.J. Walker added 7.
All of that success and points didn't mean a thing early on as the Seminoles found themselves struggling both sides of the ball - going down 21-3 late in the second quarter before a fake punt call effectively saved the day and led to a touchdown before the half by Devonta Freeman as part of 17 unanswered points that cut the deficit to one. The Seminoles finished with as many turnovers as field goals, leading to 21 Virginia points. Jerome finished 2 for 11 for 6 points to go with 6 assists and four rebounds.
"My teammates had confidence in me, and I had confidence in myself", Key said.
Kyle Guy has been scorching from three-point range this season.
Wahoo fans hope the fizzling continues all season long.