An early goal from Yann Kermorgant and a last-gasp Adrian Popa strike was the difference as Reading emerged from Hillsborough 2-0 winners.
The play-off tussle ended in the favour of the Royals, who turned in an assured first half display that effectively sealed the points.
Wednesday dominated the second period and were by far the better side but chances were few until a late rally and Reading took the honours to strengthen their top six slot.
Both teams showed their intent with so much at stake, each making early inroads to the other’s backline.
Danny Williams spooned over from a pacey Royals counter before Jordan Rhodes sent a header into the midriff of Ali Al Habsi.
But it was Reading who hit the front from their next attack on 13 minutes.
John Swift played a long ball across the field to Kermorgant and the veteran striker finished with some aplomb into the far corner.
Wednesday were rocked by the setback and upped the ante in the final third – Adam Reach fired narrowly wide and Sam Winnall tested Al Habsi from distance.
The breakthrough almost came on 24 minutes when Morgan Fox let fly from range but the ball crashed back into play off the post.
Again the Owls went close before half time as the visitors had Al Habsi to thank for a stunning save that denied Rhodes’ clever angled header.
Rhodes was just off target from a Barry Bannan set piece as Wednesday bossed possession following the restart.
Callum McManaman was introduced from the bench on the hour as the hosts sought a way back into the contest but Reading held firm in defence.
The Berkshire outfit also looked dangerous on the break and Swift went close after a jinking run into the box.
Still Wednesday asked most of the questions and Liam Moore cleared off the line from the lively McManaman.
A late onslaught saw substitute Steven Fletcher hit a snapshot that deflected off Tyler Blackett and over before the Owls three times came close to levelling.
First McManaman was thwarted by Al Habsi, then the shot-stopper denied Rhodes before keaving the best for last by producing the save of the match to keep out a Buckley header.
Man of the match Al Habsi sprung to stop another McManaman effort and from the resulting corner Keiren Westwood went upfield and Reading cleared to substitute Popa, who raced into the Owls’ penalty area to put the game to bed.
Wednesday: Westwood, Hunt, Loovens (Nuhiu 90), Lees, Fox, Buckley, Bannan, Jones (McManaman 60), Reach, Rhodes, Winnall (Fletcher 78)