Quick out of the blocks, the visitors raced into a two-goal lead thanks to emphatic strikes from Bersant Celina and Jay Fulton.
Taking time to get to grips with their opponents, the green and whites grew into the match as the half progressed and grabbed a goal back just past the half-hour mark through Tom Bradbury.
Threatening to swing the pendulum of momentum, the near full-strength opponents restored their two-goal advantage just before the break courtesy of Fulton’s second of the evening.
The deep-lying midfielder completed his hat-trick after the restart before substitutes Barrie McKay and Courtney Baker-Richardson rounded off the scoring to inflict a first pre-season defeat for Yeovil.
With two wins from two coming into the clash with the Swans, Darren Sarll stuck with the core of the side that has started throughout pre-season so far.
Youngsters Gabby Rogers and Nestor Shako both came into midfield, with an unnamed trialist partnering Rhys Murphy up front.
With the Championship outfit representing Yeovil’s toughest test in the build-up to the 2019/20 campaign, Steve Cooper’s side were immediately on the offensive as the sunset over Huish Park.
Zipping the ball around confidently on a freshly watered pitch, the visitors took just four minutes to open the scoring.
Ollie McBurnie’s hold-up play allowed his team-mates to join the attack and after finding Wayne Routledge, his through ball put Celina racing in on goal with a composed finish to follow.
Showing no sign in letting up, the Welsh outfit remained on the offensive and doubled their lead before the 10-minute mark.
Finding a yard of space on the edge of the box, Fulton wasted no time in superbly curling an effort into the top corner to give Stuart Nelson no chance between the sticks.
With Swansea threatening to run away with the match, the Glovers had Nelson and a slice of luck to thank for it remaining 2-0 as the half progressed.
Town’s stopper first had to be at his best to parry away McBurnie’s low shot from close range before the rub of the green denied the visitors a few minutes later.
Allowed spaced to shoot from 20 yards, Celina was denied a second of the night when his venomous hit cannoned back off the post and away from danger.
Ending a flurry of attacks from the Welsh opponents, the Glovers then had their best spell of the half as they started to enjoy some territory and possession.
Stitching together some neat passing passages a goal was soon to follow thanks to a well-executed set-piece.
Carl Dickinson’s inch-perfect delivery was attacked by Bradbury who marked his first appearance at home as an official Glover with a tidy headed finish.
Surging in confidence Yeovil looked to completely wipe out Swansea’s advantage and almost did so when another Dickinson delivery was this time volleyed a few yards wide by marksman Murphy.
However, having battled back into the match a set-piece at the other end returned the deficit to two goals as Fulton poked home from virtually the goal line after McBurnie’s header from a Matty Grimes corner was initially well-saved by Nelson.
Making just one change at the break as one unnamed trialist replaced another in attack, it was a Swansea substitute who had an immediate impact on proceedings.
Joel Asoro won his side a free-kick close to the byline and from Celina’s low delivery Fulton emphatically ensured he would keep the match ball by firing in off the bar.
Back in the ascendency, the visitors could’ve further added to their lead but for some determined keeping from an on-song Nelson.
The home keeper had to be at his best to deny McBurnie, Routledge and George Byers with smart stops to keep the score respectable.
Entering the final half an hour with Swansea boasting a completely changed outfield and Sarll also utilising his bench to leave only Bradbury, Nelson and Nestor Shako on the pitch, the much altered Swans added a fifth.
McKay intercepted Bradbury’s pass and after racing into the box calmly picked out the bottom corner, before Baker-Richardson added a sixth in stoppage time to round off the scoring.
Yeovil Town: Nelson; Alcock (Fleming 65′), Bradbury, Dickinson (Calverley 76′); Shako, Skendi (John 63′), Collins (Trialist 76′); Ojo (Trialist 59′); Rogers (Seager 59′); Murphy (Duffus 76′), Trialist (Trialist 46′).
Subs not used: Arnold.
Swansea City: Nordfeldt; Roberts (Naughton 46′), van der Hoorn (Cooper 62′), Rodon (Harries 62′), Bidwell (John 62′); Fulton (Evans 62′), Grimes (Byers 46′); Routledge (McKay 62′), Celina (Dhanda 62′), Dyer (Asoro 46′); McBurnie (Baker-Richardson 62′).
Subs not used: Mulder, Cooper, Harries.