The right-back has been one of the surprises of the season, carving out a role for himself under Ange Postecoglou.
Ralston has made 19 appearances so far this season.
The 22-year-old’s contract expires at the end of the season.
"My focus is trying to make sure that he continues his development,” Postecoglou said.
“He’s been fantastic, he wants to learn every day, he works hard in every game he gives everything.
“When contract negotiations happen they take care of themselves.
“There’s very little need to have any angst about it – the club has a lot of faith in Tony, that’s why they gave him a contract before I started.
“I gave him a chance and he’s taken the opportunity with both hands.”
Meanwhile, Celtic have been linked with a move for Derby County left-back Lee Buchanan.
The Scottish Sun report he club have had the 20-year-old watched.