The Socceroos captain is set to join Villa from Crystal Palace.
Jedinak was pictured at Villa Park before the Birmingham club's 1-1 draw with Huddersfield Town on Wednesday night as his move to the club nears completion.
It is thought that a fee and personal terms have been agreed between Villa, Jedinak, and Crystal Palace, and that international clearance is all that is holding up the deal.
Jedinak, Palace's captain in recent years, has been deemed surplus to requirements by manager Alan Pardew and had the armband taken off him in favour of Scott Dann earlier this summer.
Postecoglou, who appointed Jedinak as the permanent skipper of Australian in 2014, believes that the switch to Villa can only be good for the 32-year-old.
The Socceroos head coach said, as quoted by ESPN: "Players are always happier when they're settled rather than a little bit of indecision or conjecture about their futures.
"If it does come to fruition and he moves to Villa ... he'll be in a good space mentally. It certainly won't affect him in any way, he's an outstanding leader and he's been fantastic for us since I made him skipper.
"He'll come in feeling pretty good about things if he's settled."
Jedinak will be a leading figure for Villa once his deal has been completed; though the captaincy has already been given to former Bournemouth skipper Tommy Elphick, Jedinak will be the midfield leader that the club has desperately needed since the departure of Fabian Delph.
He has experience of being a mainstay in the Palace team which won promotion from the Championship four seasons ago, and, like Elphick is proving to be in defence, will be the calm head that Roberto di Matteo needs in midfield.