McSwain (7-2) struck out seven and did not yield a walk in recording his second complete game of the season and picking up his league-leading seventh win on the mound.
"Tonight was certainly not our night but this is a long series," head coach Greg Frady said. "I can say that we're going to come out tomorrow with the focus and energy needed to compete tomorrow. I talked about that with our team and that's what we expect."
The game remained scoreless through the first five innings, as Panther starter Justin Malone (1-2) matched McSwain by allowing just three hits over the first five frames.
The Seahawks pushed the first two runs of the game across in the sixth on an infield single and a bases-loaded walk for a 2-0 lead.
With two outs in the seventh, UNCW exploded for seven straight runs on six hits, highlighted by Thomas Pope's two-run triple.
Malone finished with six strikeouts over 6.2 innings, walking two.
The Panther offense could not break through in the later innings against McSwain, adding three hits but grounding into double plays that ended the seventh and eighth.
The Seahawks added six more runs in the ninth inning, led by Corey Dick's two-run homer.
GSU has now dropped six straight in the series with UNCW.
The teams continue their series Saturday at 1 p.m. at the GSU Baseball Complex.