The 34-year-old from Goldthorpe was promoted from under 16s coach to the first team dugout on a temporary basis in January and helped the Reds to promotion three months later.
His position has now been made permanent and he will work alongside head coach Daniel Stendel and coach Chris Stern as Barnsley enter the Championship.
Tonge told the Chronicle: “It’s a bit of a cliche but, for me to be part of the first team staff at Oakwell, is a bit of a dream come true. When I joined the academy as a coach, I didn’t expect it to happen so quickly but I came in in January and, after the success we had as a club, I am glad that the gaffer wanted to keep me with the first team. I am really happy.”
Jordan Foster will join as first team sport scientist, to assist head of sports science Luke Dopson while Nathan Kirby strengthens the analysis department after a successful internship during 2018/19.