Wanderers started very well and scored after just two minutes of play, as Darcy combined with King-Harmes expertly, before the young Wanderers rifled his shot into the the top corner of Barnsley's goal.
It began to get very intense after the initial goal, as Barnsley looked to press Nicky spooner's men and pressure the ball as much as possible.
However, resolute defending from the Whites saw the pressure subside after a few nervous moments.
Moving into the second half and Wanderers extended their lead through Ronan Darcy.
Max Broughton flicked on a through ball into the path of Darcy, who reacted first by running in behind and forcing the keeper to spill the ball into the path of King-Harmes who dispatched it into the goal with ease.
The home side did have a glimmer of hope when they were awarded and scored a penalty with minutes to go in the clash.
However, the Whites held on and earned three points in a very tough fixture.
Wanderers XI: James, Toney-Green, White, Broughton, Osigwe, Boon, King-Harmes, Smith, Holmes, Darcy, McKenzie.
Substitutes: Graham, Edmondson, Alexander, Sterling, Sithole