Defeats for Leyton Orient and Rotherham mean the Bees are back in the second tier for the first time since 1992-93.
Most neutrals would not begrudge the West London side promotion, after last season's disappointment when a last minute penalty miss and a goal from Doncaster saw the Yorkshire side promoted instead.
The final whistle saw a pitch invasion at Griffin Park but Brentford had to wait for confirmation of Rotherham's result at Wolves, with the Millers losing 6-4 despite a late fight-back.
The play-offs look like being between Orient, Rotherham, Preston - all guaranteed a play-off spot and either Peterborough or Swindon. Peterborough play on Saturday after Swindon closed the gap on them to four points after winning against Coventry. Peterborough can extend that gap to seven points if they win at Bradford City.