The 21-year old impressed in his handful of appearances in the Gers' Third Division title-winning season, picking up two man of the match awards from his final four games.
Mitchell put pen to paper on a new one-year deal on Tuesday and he admitted that he was thrilled to do so.
"I'm absolutely delighted to be staying. It's a privilege to be playing for this club and it's great to be staying for another year," he told the Daily Record.
"If I had it my way I'd have signed a lifetime contract with Rangers already because I love it here.
"To be getting another year is brilliant for me.
"It gives me that bit of stability and now I want to kick on."