Doncaster slipped into the bottom three of the Championship after losing their fifth straight game.
Sheffield United took the lead when Gareth Roberts diverted a Danny Webber cross into the net with James Beattie and Billy Sharp lurking.
Doncaster rallied but Darren Byfield missed from a yard after Paddy Kenny had parried Matthew Mills' header and Brian Stock hit the woodwork.
Stephen Quinn smashed home the second goal after Beattie had played him in.
Doncaster manager Sean O'Driscoll:
"I'm disappointed. We didn't put the ball in the back of the net, but I'm pleased with the performance.
"I thought that our discipline was really good, which it had to be. They are the foundations that you need to keep whether you're playing good, bad or indifferent or winning or losing games.
"We tried to do the things that were right and on another day we would have scored two or three. We have to dust ourselves down and move on."
Sheffield United manager Kevin Blackwell:
"We created better chances than them and every time I thought we could score.
"The system that they play here causes people problems but we acquitted ourselves well and every time we went forward we looked threatening.
"Every game is a massive result when you're at Sheffield United. Yorkshire derbies and tough games to win and if you come away from home and get three points then you're delighted."
Doncaster: Sullivan, O'Connor, Mills, Lockwood, Roberts, Wilson (Guy 83), Stock, Wellens, Byfield, Price (Hayter 80), Woods (Heffernan 80). Subs Not Used: Chambers, Van Nieuwstadt.
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