After discussions held on Thursday, the Championship outfit have confirmed that they have opted to move in a different direction ahead of next season.
CEO Lee Hoos told the club's official website: "On behalf of the board we are hugely grateful to Ian for his incredible efforts during his time with us.
"He joined us at a critical stage as we looked to reduce the wage bill, bring in younger talent and remain competitive on the pitch at the same time. That is no easy task and it was down to his desire, love for the club and hard work that he achieved those goals.
"However, we are now looking to take the next step as we continue to work through what is a vital period of transition for the football club."
QPR ended the campaign in 16th place in the second-tier standings.