The game was over as a contest after 30 minutes - by which time the Pilgrims led 3-0 - and although Wednesday were much improved after the break, Marcel Seip's last-minute header put the seal on an easy victory.
Playing with driving rain at their backs, Argyle took the lead after 15 minutes when Mark Beevers, recalled to the Wednesday side in place of injured Richard Wood, put through his own net.
Beevers deflected Jamie Mackie's shot into his own net after a goalmouth scramble caused when goalkeeper Lee Grant failed to hold on to Paul Gallagher's low shot.
The second goal came 10 minutes later and was the pick of the quartet.
Chris Clark started the move, bringing the ball inside before sending Mackie away on the right wing to supply the perfect cross for Gallagher that the Argyle striker tucked away for his fourth goal in six games.
Having thrown away a 2-0 lead at Bristol City the previous Tuesday, Argyle were grateful for a quick nerve-settler.
This time Mackie was rewarded for a fine first-half performance after netting from close range after Grant had saved a spectacular volley from Rory Fallon following Luke Summerfield's corner.
Wednesday regrouped at the break and sent on Francis Jeffers and Jermaine Johnson, who shot narrowly wide and then brought a good save from Argyle goalkeeper Romain Larrieu.
The Pilgrims eased down, allowing the opponents to have more of the game, and only occasionally troubled Grant on the break before adding final goal to their tally.
Dutch centre-back Seip was allowed a free header from another Summerfield corner to rubber-stamp the Pilgrims' fourth win in their last five games - a run that has seen them rise from bottom of the table to fifth in just three weeks.