King, 30, served nine months behind bars after being found guilty of actual bodily harm and sexual assault of a woman in December 2008.
King had his contract terminated by Wigan when he was convicted, and the Lactics chairman Dave Whelan hit out at the striker, saying "he should never play football again".
However, the ‘bad boy’ of English football, who has 13 previous criminal convictions, is hoping to make a return to the professional game, and QPR manager Neil Warnock is ready to pounce.