Uwe Rosler's Bees continue their hunt for a first away win of the season and will have been left disappointed to have returned home empty-handed.
Billy Paynter powered home a header from Martin Woods' cross after 86 minutes to complete the turnaround for lacklustre Doncaster.
A stunning 25-yard strike against the run of play from David Cotterill 15 minutes from time levelled the score and sparked Rovers into life.
The visitors took a well-deserved lead on the stroke of half-time when Adam Forshaw split the Rovers' defence with a well-weighted pass and sent Jonathan Douglas clear to clip the ball over Rovers goalkeeper Gary Woods.
Brentford controlled possession for the majority of the contest, punishing deep defending from the hosts, but failed to craft many clear-cut chances.