The Seminoles (35-6, 19-4 ACC) strung together a trio of big innings, scoring five runs in the third, three in the sixth and four in the eighth. The 13 runs allowed by Carolina equaled a season-high for the nation's top pitching staff in terms of earned run average.
In addition to Guinn, left fielder Mike McGee went 3-for-5 with two RBI. Five other Seminoles added two hits on the night.
Seminole righty Geoff Parker (4-1) went 5 1/3 and held the Tar Heels to two runs on seven hits and three walks. Reliever Ryan Strauss picked up his fourth save with 2 1/3 shutout innings.
UNC right-hander Adam Warren (6-1) suffered his first career loss in the second-shortest start of his career. Over just 2 1/3 innings, he allowed five runs on a career-high-tying seven hits to drop to 19-1 in three seasons as a Tar Heel.
Dustin Ackley led Carolina with three hits on the night and is 6-for-8 in the series. Right fielder Tim Fedroff added two hits.
The Seminoles grabbed a 1-0 lead in the first with a two-out rally against Warren. Catcher Buster Posey singled to left and scored on a double down the right field line by Guinn, but right fielder Jack Rye was thrown out at the plate trying to score from first on the play to end the inning.
Florida State broke the game open in the third with five runs, four of which were charged to Warren. Center fielder Tyler Holt led off the inning with a solo shot to left field for the first home run allowed by Carolina in 15 games. Posey followed a single by Jason Stidham and a two-base throwing error with an RBI groundout back to the mound to give FSU a 3-0 lead.
A single by Rye and the second double of the game by Guinn put a pair of runners in scoring position and ended the day for Warren. A two-out balk by reliever Colin Bates and RBI singles from designated hitter Tommy Oravetz and third baseman Stephen Cardullo pushed the lead to 6-0 and closed the five-run inning for the Seminoles.
The Tar Heels got on the board in the bottom of the inning when shortstop Garrett Gore and Ackley opened the frame with back-to-back singles, and Fedroff came through with a base hit up the middle to cut the FSU lead 6-1.
The Seminoles put three more on the board in the sixth to grab a 9-1 lead. Cardullo opened the frame with a single to left center and scored from second on a single through the right side by Stidham, who later scored when Rye reached on Gore's second throwing error of the night. Guinn followed with his third double to drive in Rye and lift the Noles to an eight-run advantage.
UNC got one of the runs back in the bottom of the inning when second baseman Kyle Seager tripled off the center field wall with one out and scored on a sacrifice fly to left by center fielder Seth Williams.
Following a 34-minute lightning delay between the sixth and seventh innings, the Tar Heels scratched out three runs to briefly get back in the game. Consecutive hits by Ackley, Kyle Shelton and Fedroff started the rally with Shelton driving in the first run of the frame with a double to right center.
After a walk to Seager, Federowicz reached on a fielder's choice to drive in Fedroff, and Mark Fleury singled through the right side on the next pitch to bring the Tar Heels within four runs.
But Florida State came right back with four runs in the eighth to put the Tar Heels away. RBI singles by Guinn and shortstop Tony Delmonico opened the scoring, and McGee followed with a two-run single to extend the lead to 13-5 for the Noles.