Rudy Gestede scored his first goal at Ewood Park for Blackburn to keep the pressure on the top six in the Sky Bet Championship.
Gestede pounced for his second league goal in consecutive games on the stroke of half-time when he headed past Ross Turnbull from six yards.
It earned Blackburn a second league win on the bounce and extended their impressive recent record to just one loss in eight.
It also keeps Doncaster in the bottom three and they have picked up just two points from 27 on the road. They remain without a win at Ewood Park.