The Irishman is one of City's longest serving players, having been signed by Peter Taylor for £50,000 from Leicester over five years ago.
After initally being an unpopular signing, Delaney then became Player of the Year in 2004 for his part in City's promotion from Division Three.
Usually a centre back, some of Delaney's 224 league appearances for the club have been at left back and in midfield. The 26-year-old has also worn the captain's armband on occasion.
Chairman Paul Duffen revealed at last night's Fans' Liaison Committee meeting that Delaney would join QPR for an undisclosed fee today - an offer the club couldn't refuse.