Chris Brunt had produced a cool strike to snatch a 64th minute goal with the Hillsborough side trying to end a miserable run with just one win from six games.
Brunt was the first to react as striker Lee Peacock flicked then ball forward as he beat the advancing Ben Foster from ten yards.
Wednesday, desperate to haul themselves up the table, should have snatched the lead in the third minute. On-loan Manchester United winger Chris Eagles produced a teasing cross from the right but David Graham steered his header against the post from six yards.
Foster should have been sent off in the 12th minute as Graham chased a Glenn Whelan pass only to be upended by the Watford keeper on the edge of the area. Referee Tony Leake produced a yellow card as skipper Whelan ballooned his free-kick high over the target.
Young produced a curling free-kick with Marlon King just failing to connect as David Lucas scooped up the ball.
Chris Brunt's free-kick from 25 yards dropped the wrong side of the bar minutes after the restart, but Wednesday almost came unstuck in the 58th minute.
King fed Matthew Spring who cut into the area before being stopped in his tracks by the combined tackles of keeper Lucas and full-back Frankie Simek.
Wednesday were fuming in the 83rd minute when Eagles was bundled over by Hornets skipper Gavin Mahon, but Mr Peake turned away their appeals.
Young had the last word as he held off his marker to turn and his shot from ten yards scraping the woodwork on its way past Lucas.