South Carolina (55-14) became the first team to ever go 10-0 in an NCAA tournament and the first since Oregon State in 2007 to go unbeaten in a CWS.
The Gamecocks' streaks of 16 NCAA tournament wins and 11 straight in the CWS are both the longest all-time.
South Carolina has the distinction of winning the last CWS played at Rosenblatt Stadium and the first at TD Ameritrade Park. Peter Mooney doubled to start a three-run third inning in the matchup of Southeastern Conference rivals and hit the Gamecocks' first home run of the CWS in the sixth.
After giving up four runs in the first inning of their opener against Texas A&M, the Gamecocks allowed just six in their other 50 innings here.
They became the sixth team to win consecutive national titles and first since Oregon State in 2006 and 2007.
Roth (14-3), who pitched seven innings against Virginia on Friday, gave up five hits and two runs before leaving in the eighth. He started last year's national championship game but didn't get a decision.
Among pitchers who have worked 30 innings at the CWS, Roth's 1.17 ERA over 38 1-3 innings the past two years ranks second all-time behind Ohio State's Steve Arlin, who had a 0.96 ERA over 47 innings in 1965-66.
Roth came in with a 0.98 ERA for the season and held Florida without a run after it got leadoff men on base in the fifth, sixth and seventh innings. Roth left with two outs in the eighth after giving up a double to Mike Zunino, who later scored on Josh Adams' single off John Taylor.
Matt Price worked 1 1-3 innings for his 20th save.
Florida starter Karsten Whitson (8-1) came out strong, mixing in his mid-90s fastball to strike out three of the first six batters.
But South Carolina scored three runs in the third after Mooney's leadoff double into the left-field corner. Mooney scored on a sacrifice fly by Scott Wingo - the CWS' Most Outstanding Player - Evan Marzilli came home when shortstop Nolan Fontana swiped at and missed Christian Walker's grounder. Brady Thomas brought in another run with his infield single.
Whitson, a freshman who was the No. 9 overall draft pick by the San Diego Padres in 2010, left with the bases loaded and two outs in the fifth. Tommy Toledo came on to strike out Jake Williams.
The Gators made it a two-run game when Zunino hit Roth's 84 mph slider into the seats in left for his 19th homer of the season - and first off Roth since April 22.
For all the great memories left behind at Rosenblatt, the Gamecocks already have created a bunch at the new stadium. There was Wingo's bases-loaded single to beat Texas A&M in the bottom of the ninth in their opener.
There was Price getting out of bases-loaded situations three times against Virginia on Friday before two errant throws on bunts produced the winning run.
And then there was Wingo throwing out runners at home from second base with the bases loaded in the ninth and 10th innings and left fielder Williams nailing Cody Dent at the plate in the 11th before Walker, playing with a broken wrist, scored the winning run in the 11th on two Florida throwing errors.