The result, with only two games left in the schedule, puts Brentford beyond the reach of Watford Ladies and Hackney Womens in second and third.
The Bees took the lead after only 15 minutes, Shannon Read cleverly staying onside before diospatching the ball beyond the goalkeeper.
Hackney had a great chance to go level when Brentford gave the ball away in the middle. A neat pass had Rebecca Verity one-on-one but a late offside flag saw the attack stopped prematurely.
Jasmine Williamson broke down the right and crossed into the middle after half an hour, Read shooting narrowly wide of the target.
Hackney went close when they broke clear but goalkeeper Hannah Iguchi saved the attempt with her feet. The following corner was nodded away by Salma Mahamud.
The second half started with a few physical challenges but The Bees kept their head and powered on. A Kasey Clifford free-kick flew just over the bar after an hour.
Williamson then collected a quick throw from Read, before squaring it for Clifford. She shot quickly and it deflected off a defender into the net to make it two-nil.
It could have been three when Clifford's cross was nodded towards goal by Ruby Sumpter. It just crept over the crossbar. At the other end, Larique McPherson-Maraj made a great block after Iguchi saved from close range.
With 10 minutes to go, Hackney were back in the game. Debora Cagnin's shot went through a crowd and found the net. Hackney looked like they were going to equalise in the final minutes but the excellent Iguchi pulled off a fine save.
The final whistle sounded soon after, confirming Will Blithing's side as Division 2 champions. Congratulations to the girls on a successful season!
Bees: Iguchi; Boparai, McPherson-Maraj, Mahamud; Abou-Abdallah, Sumpter, Green, Azam; Clifford, Read, Williamson
Subs: Allidina, Idowu, Jaffa, O'Connor, Bah