But Gorkss ensured Rangers claimed a fourth away win in six matches when he met a corner from substitute Alejandro Faurlin with a firm near-post header.
Simpson opened the scoring in the 10th minute with a cool left-footed finish after he had been released by the impressive Adel Taarabt.
But Johnson pulled the Owls level within three minutes as he converted a teasing left-wing cross from Darren Potter.
Wednesday struck the woodwork on two occasions and the visitors were also denied by the post as chances came at either end, yet there were to be no further goals until Gorkss' late intervention.
Owls boss Brian Laws opted to name the same starting XI that earned a 1-1 draw at Bristol City last weekend.
Gavin Mahon returned to skipper the visitors after missing two games with a hip injury and there was also a recall for Peter Ramage, with Gary Borrowdale and Faurlin the men to miss out.
QPR started brightly and took the lead when Simpson latched on to a neat through ball from Taarabt before driving his shot beyond Lee Grant.
Wednesday almost conceded a second two minutes later when Wayne Routledge found space in the area and fired against the upright.
But the hosts drew level in the 13th minute when Potter's cross found Johnson and the Jamaica international's shot sneaked into the far corner.
Luke Varney almost put the Owls ahead in the 24th minute following a fine solo run, but Cerny managed to get a hand to his shot and tip it on to the near post.
QPR then lost Fitz Hall to an injury, with Matthew Connolly coming on in his place, before Ben Watson's 25-yarder brought a fine save from Grant.
Johnson saw a shot whistle wide at the other end, while Grant made another useful stop to deny Routledge as an open first period drew to a close.
The lively Johnson tested Cerny again five minutes after the interval and Potter curled a free-kick narrowly over the bar as Wednesday enjoyed a prolonged spell of pressure.
Rangers were finding it difficult to stem the tide, although they offered a reminder of their attacking threat when a swift break ended with Taarabt firing into the side-netting.
Simpson then created space for himself with a delightful piece of skill, but his shot was comfortably pouched by Grant.
The Owls responded by striking the woodwork for a second time in the 64th minute - Tommy Miller the unfortunate party on this occasion as his powerful 20-yarder cannoned off the post.
Leon Clarke came off the bench for Wednesday with 14 minutes remaining and almost made an immediate impression with a shot that deflected wide.
But Gorkss had the final say as he nodded home Faurlin's corner to secure victory for Rangers.