Striker Lee Bradbury ended his goal drought in style with a hat-trick to earn Portsmouth their fourth successive win.
It boosted Pompey's hopes of avoiding relegation - and sent bottom-placed Swindon slipping closer to Second Division football next season.
Bradbury, who returned to Fratton Park in October from Crystal Palace, had not scored for nearly three months and had found the back of the net only once in the last 22 league games.
But he was in deadly form against lowly Swindon as he grabbed three goals inside nine minutes.
Bradbury's strike partner Steve Claridge had secured all the headlines in previous weeks with 12 goals in 15 games while Bradbury's only goal came at Norwich on January 3.
But the big striker fully restored his confidence in front of goal by scoring twice in two minutes prior to half-time before adding a third with a header on 49 minutes.
Bradbury grabbed his first and Portsmouth's second five minutes before the interval as he robbed Swindon defender Mark Robinson before firing home a shot inside the post.
He wasted no time adding a second two minutes later as he seized on Claridge's cross in the six-yard area before coolly waiting for goalkeeper Frank Talia to commit himself and prod home a shot from close range.
And the former Manchester City forward rounded off a memorable afternoon for himself and 15,305 crowd by completing his hat-trick four minutes after the interval by heading in at the far post from Kevin Harper's inviting cross from the right.
Portsmouth captain Adrian Whitbread had begun the goal flurry in the 30th minute when he slid in for his first goal of the season after Ceri Hughes' cross was flicked on by Thomas Thogersen.
Jimmy Quinn's side badly missed leading scorer Chris Hay who had completed a £75,000 move to Huddersfield on transfer deadline day.
But they grabbed a late consolation in the 69th minute when on-loan Wimbledon striker Wayne Gray hooked home a shot inside the post following winger Michael Meaker's cross.