The Millers just about shaded a mediocre first half, but despite several good chances they could not add to a 12th-minute lead given to them by Mark Hudson.
Hudson was involved in all the early action, firing wide in the first minute and then floating in a free-kick which Reuben Reid headed just over. The deadlock was broken when Reid cut in from the right and crossed for Hudson to fire home.
Macclesfield’s main threat came from Jamie Tolley who was foiled by a great tackle from Jason Taylor after 15 minutes and then Tolley was inches wide of the target with a long-range effort three minutes later.
The second half was even shorter on quality than the first, and nervy Rotherham looked like giving it away as the visitors pushed forward and substitute Tom Elliott whistled a shot narrowly wide.
However, Reid settled Rotherham’s nerves after 77 minutes. Drewe Broughton headed on a long ball from the right and Reid calmly lifted the ball over the goalkeeper and into the net.