The Plymouth Argyle coach is the third new member of Rob Page’s coaching staff and will take up his new position when the players return to training tomorrow.
Harbin’s appointment comes after the addition of Dave Timmins earlier today and Paul Bodin last month.
Yorkshire-born Harbin emigrated to Australia when he was ten and has worked as a coach within both Football and Rugby, with his most notable achievement coming when he was promoted to the Premier League with Crystal Palace, working alongside Iain Dowie.
Harbin will be responsible for looking after the players’ fitness, strength and conditioning, as well as their psychological welfare.
Upon the appointment of Harbin, Valiants’ boss Rob Page said: “I’m delighted to welcome John to the coaching staff, he’s someone I have high regards for after working with him before at Coventry.
“Having someone of his experience around the place can only have a positive effect on the club so it’s a great coup for us.”