It was typical end of season fare from two teams with nothing at stake and although Rotherham had the advantage of an eighth-minute lead, they should have gone on to win far more comfortably.
Jamie Green grabbed the only goal, his first ever in the league, when Dale Tonge's shot was blocked. Barnet failed to clear the danger and Tonge played a ball across the area for Green to drive into the net.
However, Rotherham were giving the ball away too easily and the visitors looked lively going forward - with Andy Warrington forced to save from Cliff Akurang and Adam Birchall's cross headed out from under the crossbar.
Rotherham should have had a second after 33 minutes, but Danny Hudson sliced his shot over the crossbar.
The visitors continued to dominate after the break and only an amazing goal-line clearance by Marc Joseph after 57 minutes denied Jason Puncheon an equaliser before Jamie Yates smashed a shot for The Millers against the post