Burton leapfrogged over their hosts as Rotherham fell to their fourth defeat in a row.
Albion took an early lead when Justin Richards sped down the right, slipped a pass to Cleveland Taylor and continued his run to turn in Taylor's drive.
The Millers' best chance came when Ben Pringle headed down Danny Schofield's cross only for Lewis Grabban to sky his shot over the bar.
Grabban almost made amends early in the second half but his shot hit the bar.
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Rotherham boss Andy Scott told BBC Radio Sheffield:
"I'm sick of saying the same thing; we just can't defend, it's driving me absolutely mad that people aren't prepared to do their jobs and put their bodies on the line.
"We got dominated in the first half because we didn't compete.
"Second half, well it's the most one-sided game you are ever going to get in a football match and it's still a worry because we just don't seem to be doing what we're supposed to do."
Burton Albion manager Paul Peschisolido told BBC Radio Derby:
"We defended absolutely gallantly - it was unbelievable the way they threw their bodies on the line. If we defend the way we did, we will progress and progress because they were absolutely brilliant.
"We had to graft as a team. I would like to have played better football and keep the ball better but ultimately we got the points.
"We got the goal when we needed it and we won ugly."