Gala Parc old boys Tyler Cooke and Kevin Lawrence were on target for Penryn against their former club as Steve Jewell's side scored three second half goals to beat Porthleven 4-1 at Kernick Road.
Josh Hoon put the home side a goal up in the seventh minute, only for Port to equalise just after half time through Freddie Williams.
But an Ed Wilton strike after the hour mark saw Penryn regain the lead, before Lawrence and Cooke struck late on to make sure of the points for Athletic.
The result flattered Penryn, but it brings to an end a disappointing run of two straight defeats for Jewell's side.
In contrast Porthleven continue their worrying slide down the table.
Dennis Annear's youngsters are without a win in their last four outings, and face another tricky game on Tuesday night when they host Wadebridge.
In glorious sunshine Port started brightly, but found themselves behind when a foul conceded wide on the right resulted in David Broglino whipping a free kick into the six yard box. Josh Hoon arrived unmarked to head past a stranded Dennis Annear.
Port, who were without regular strikers Jordan Annear and Christian Blango, almost equalised when Sam Kay headed against the upright after Penryn failed to deal with a loose ball in the box.
But the visitors were forced until wait until after half time before drawing level. Tom Annear's pinpoint cross delivered at pace found the head of Williams, who planted a close-range header past Chris Symons in the Penryn goal.
Port pressed hard for a second, but Penryn regained their lead when Wilton's pace allowed him to beat the offside trap just inside the Port half, race clear of his marker and slide a shot past Annear from the edge of the box.
Lawrence made sure of the points soon after when he caught centre back Jack Glover in possession on the edge of the area, before fashioning himself a yard of space and curling a shot into the far corner, past Annear's outstreched arm.
Tyler Cooke's goal in stoppage time, tapped in from all of eight yards out after Port were caught cold at the back, rounded off a miserable afternoon for the Fishermen.
Penryn: C Symons, D Blizzard, R May, J Hoon (T Cooke 76), B Oliver (c), S Johnston, D Band, G Hobbs (W Scoley 81), K Lawrence, E Wilton, D Broglino. Subs (not used): P Davey, K Faulkner.
Porthleven: D Annear, C Wormington, L Hunter, D Tarrant (M Best 75), J Glover, J McCardie, T Hawkins (A Orchard 75), T Annear, F Williams, S Kay, D Greet. Subs (not used): None.