An anterior cruciate ligament injury sustained against Chelsea last September restricted the striker to just four appearances in his first season at Loftus Road after joining from Fulham.
Now fit and back in action, Johnson wants to repay the faith shown in him by helping Harry Redknapp's side make an immediate return to the top flight.
"QPR stood by me last season and I will do the same by them," Johnson told the Daily Express.
"I feel I owe them.
"I want to help them get back into the Premier League, where we belong."
Johnson, 32, spent four years at Premier League new-boys Palace between 2002 and 2006 and helped the club clinch promotion to the Premier League via the Championship play-offs in 2003-04.