The striker is set to complete a £4m move to Saint Mary's.
The player has already completed a medical with the Saints and agreed personal terms ahead of a £4m move to Saint Mary’s.
Austin’s current deal is set to expire in the summer, and it had been thought that he would be staying at Loftus Road until then and make his move to a new club in the summer.
However, it now seems that won’t be the case, with Southampton having moved quickly to secure the striker in the January transfer window, according to Sky Sports.
The move may have been brought about by Jay Rodriguez’s persistent injury problems, with the striker yet to return fully from a foot injury picked up in November.
Austin’s arrival is also likely to put further speculation on the future of forward’s Shane Long with him having been linked with a move away from the club this month.
The Sun this week reported that Liverpool are mulling over a move for the Republic of Ireland striker, and perhaps Austin’s move could see him pushed closer to an exit.