Striker Calvin Zola and winger Jacques Maghoma shared the goals in an impressive display by Gary Rowett's side.
Oxford's goal enjoyed a charmed life as Burton made the early running. Visiting goalkeeper Ryan Clarke almost fumbled a punt forward from defender Marcus Holness over the line and then breathed a huge sigh of relief as full-back Damien McCrory's left-foot shot from the edge of the area shook the crossbar.
There was nothing Clarke could do to prevent a stunning opener when Zola took McCrory's cross on his chest and turned to score with a 22-yard volley in the 26th minute. And the keeper was comprehensively beaten for the second time on the stroke of half-time, this time Zola was the provider as he teed-up Maghoma for a 20-yard shot into the top corner.
Substitutes Tom Craddock and Jon-Paul Pittman both had shots off target as Oxford made a better start to the second half. Pittman also had a fierce shot tipped over by Burton keeper Stuart Tomlinson but Burton stormed back to score twice in a minute.
Maghoma curled home a 20-yard free-kick in the 65th minute and then provided the cross for Zola to volley his second.