Rangers boss Stuart McCall says he feels sorry for Gael Bigirimana, but admits he should never have been signed.
Chris Gunter will stay at Reading, after the club took up the option to extend his deal by another year.
Rigg joined the Barclays Premier League strugglers from Manchester City last season to renew his partnership with then Rangers boss Mark Hughes.
But following Harry Redknapp's appointment as Hughes' successor last month the club have opted for a further change.
They confirmed Rigg's departure in a brief statement on their website that said: "Queens Park Rangers Football Club can confirm that it has been agreed that Mike Rigg will leave his position at Loftus Road."