A statement from the 31-year-old said: "At this stage of my career, this opportunity may not come around again. A new challenge, a new opportunity, and a chance to play under the stewardship of one of the most respected managers in the game.
"I hope the management of West Bromwich Albion will accept my transfer request in the manner that I have requested it.
"I have not taken this decision lightly and I would like West Bromwich Albion to accept what, in my opinion, is more than a reasonable offer from QPR for me."
The Nigerian has scored five goals in the Premier League this season.