The 25-year-old has been little more than a fringe player at City and could now link up with former manager Mark Hughes at Loftus Road.
It is understood a fee between £2.5million and £2.75million has been agreed for the defender, who now has permission to speak to the west Londoners.
There had been reports of a £3million fee and wages of up to £80,000 per week, but it is understood that Onuoha would earn significantly less than reported.
While an offer has been accepted for the former Sunderland loanee, a deal is by no means done as he considers whether he wants to move south.
Hughes has confirmed talks are "progressing" and hopes to speak with Onuoha about a potential move on Thursday afternoon.
"We've obviously expressed an interest and I think it is progressing," the Welshman said.
"I don't think we are at a point where we can confirm or really say it will definitely happen.
"We're hopeful but it has not been confirmed yet.
"I would like to think [we are closer to agreeing a deal].
"There has been conversations between both clubs and if we can make it happen we will be delighted."
He added: "I am not sure if we have totally been given permission to speak to the boy but certainly the two clubs are talking.
"Faxes are going back and forth, emails and what have you.
"I would like to think at some point today [Thursday] I'll be able to speak to him directly and make him understand what we want to do here."