Striker Ryan Lowe was the hero, scoring two goals and creating the third, as Chester ended their eight-game winless streak.
Brentford should have taken the lead in the 24th minute when Marcus Bean side footed an effort against the bar from inside the six-yard box.
And they were left to rue the missed opportunity when Chester went ahead a minute later, Eddie Johnson touching the ball into the path of Lowe, who raced through to finish confidently past Ben Hamer.
Chester doubled the advantage in the 57th minute when a right-wing cross from Lowe was met by a bullet header from Kevin Roberts, which gave the visiting goalkeeper no chance.
And Lowe rounded things off on the hour-mark, beating the offside trap to race on to Mark Hughes pass and slide the ball in off the post. Chester could even afford to miss a great chance late on as Paul Rutherford’s effort struck a post.