Chad Tworek (2-0) worked the first seven innings, holding the Panthers to five hits while walking one and striking out seven.
Justin Tworek held South Florida hitless in the final two innings to earn his second save.
The Panthers had scoring opportunities but left seven runners on base in seven innings.
With the win, the Eagles clinched a spot in the state tournament.
Polk State scored a pair of runs in the bottom of the second inning. Cole Warken lined a single to right field and scored on Joe Strzelecki's double to right. He moved to third on a sacrifice by Yeison Gomez and scored on an error.
The Eagles got on the scoreboard once more in the bottom of the eighth when Skylar Frey singled, moved to third on a wild pickoff throw to first base, and scored on Brandon Gali's single on a 3-2 pitch.
Gali went 2-for-4 with an RBI.
Strzelecki had an RBI and a run scored along with his double.
Cole Warken singled, walked, and scored.
Frey had a single, a run, and an RBI.
Gomez and Isaiah Cullum each singled.
The Eagles (34-13, 19-7, No. 3 FCSAA) face South Florida once more this season on Friday at 6 p.m. in Avon Park.