Forest Green were relegated from League One after Barnsley handed out a 5-1 thrashing to remain in the promotion hunt.
A double from Adam Phillips alongside goals from Slobodan Tedic, James Norwood and Devante Cole condemned Rovers to their 28th defeat in 42 games.
The Tykes opened their account in the eighth minute when Tedic headed home a Luca Connell corner six yards out.
They doubled their lead via the aid of a deflection following a fine Phillips volley that wrongfooted Rovers goalkeeper Ross Doohan.
The hosts’ inability to defend set-pieces was evident again before the break when former Rovers forward Norwood flicked another Connell corner into the far corner.
Barnsley made it four after the break when Phillips’ penalty was saved by Doohan but the midfielder tapped the rebound home.
Rovers substitute Reece Brown netted his third goal of the season when he curled home a fine effort into the far corner from the edge of the area.
The visitors added a fifth when Cole bundled home a Jordan Williams cross.
Barnsley remained fourth, four points off the automatic-promotion places.
