Having suffered cruciate ligament damage in just his third game for the club, the 32-year-old former England international could only watch on helplessly as the west Londoners were relegated last season.
Johnson returned to the fold and impressed asHarry Redknapp's side got life back in the second tier off to a promising start.
The hosts, including former captain Joey Barton for the first time in 447 days, showed a steely determination rarely seen during their tumultuous two-year stay in the Premier League, refusing to crumble after impressive debutant Atdhe Nuhiu gave Wednesday an early lead.
Nedum Onuoha drew QPR level in the 40th minute when he directed home a Junior Hoilett strike, before Johnson netted his first goal since November 2011 three minutes later.
Substitute Jacques Maghoma rattled the post as Wednesday pushed for a leveller but QPR held firm to pick up their first win since March 9.
Talk in the build-up surrounded QPR's surprise inclusion of Barton - his first appearance for the club since an infamous violent outburst at Manchester City on the last day of the 2011/12 season.
Barton spent last term on loan at Marseille and declared in May he would never play in the Championship.
Yet today he was one of six changes Redknapp made to the side that started the last game of last season.
Not only that, he played alongside summer signing Karl Henry - someone he has had public rows with on and off the pitch in the past.
Barton could yet leave before the transfer window closes but looked focused on the job in hand this afternoon.
Hoilett and Johnson had chances as QPR began brightly, but Nuhiu, who spent time on trial with Premier League new boys Crystal Palace before joining Wednesday, stabbed wide in the 13th minute.
It was a warning shot QPR failed to heed and the 6ft 6in striker opened his account seven minutes later, cutting in from the right before firing an excellent driven effort past Robert Green.
The Hoops wasted a fine chance to level as the half-hour mark approached, with Barton sending an exquisite right-wing cross that Hoilett could only fire over.
The Rs continued to push and, after Michail Antonio's penalty appeals were waved away, managed to level inthe 40th minute.
Hoilett, proving a constant threat on the left flank, cut inside and struck goalwards, with defender Onuoha directing home from close range - his first goal since November 2010.
The home fans were again on their feet three minutes later.
Chris Kirkland did well to deny a point-blank Barton header, but the ball fell kindly for Johnson to mark his first appearance in 11 months with his first QPR goal.
Wednesday returned for the second half strongly and Antonio should have levelled when put through clear on goal shortly after the restart.
Maghoma, on as a first-half substitute for the injured Jo Mattock, was booked for taking a tumble over Barton's leg in the box, before then smashing a shot off the goal frame.
Redknapp introduced new signing Charlie Austin for the remaining 20 minutes and the former Burnley striker forced Kirkland into a save shortly after his introduction.
He headed just over as the clock wound down but despite his best efforts,