Resounding win leaves U's virtually assured of League One football.
The U’s had an early sight of goal after just four minutes as Ibehre beat the offside trap to bear down on goal. He initially hesitated, but still shook off his man to get away and slid his shot agonisingly past the post.
It would need a seventeen goal turn around on the final day of the season to change things now and the U's can breathe easier ahead of their trip to Walsall next week.
The U's had faced a similar task in the final home game of the season against Shrewsbury a year ago, but this match couldn't have been more different as the U's are nearly completely assured of League One football.
Freddie Sears extended the U's advantage before Sam Walker saved a Brentford penalty on a memorable afternoon.
Needing a win, the U's raced into a 3-0 lead before the Bees grabbed one just before half time.
Colchester United virtually secured their League One safety on Saturday afternoon as they ran out resounding 4-1 winners against already promoted Brentford at the Weston Homes Community Stadium.
After that, there followed a period of play where the Bees confidently stroked the ball around without really seeking to penetrate the U’s defence.
The Bees first genuine chance came midway through the first half, as a free kick given against Wynter saw Douglas strike one from distance that Walker fended away to safety.
At the other end, Gilbey fed a ball between full back and centre half that found Watt. He in turn set up Sears, who forced a fine low save out of Button at the base of the post.
The U’s got their noses in front on the half hour mark. Wilson swung in the free kick and Bean dived bravely in to score the header past Button.
Then Watt almost got in himself as he slipped at first but forced the keeper into a great save.
But the home side didn’t have to wait long for their second goal. Another set piece and another goal, as Sears crossed for Wynter to bury a powerful header past the helpless Button.
The visitors went close with a curled effort from Donaldson that dipped just over the bar, before the U’s added a third before half time.
Watt won the penalty as he was knocked over in the box and, although he wanted to take it, Sears was given the honours and he smashed home to make it three.
The game was not done and dusted though, as the Bees pulled one back just before half time. The ball fell to Dallas who powered one into the top corner on the half volley.
There was a change for Col U at half time, as Wilson was replaced by David Wright. The experienced man slotted into central defence, with Wynter going to right back.
The Bees dominated possession after the restart, but the U’s stood strong in that first quarter of an hour.
But there were no real clear cut chances until the U’s extended their advantage twenty minutes into the second half.
A defensive mistake saw Sears push the ball past Button and drill the ball into the empty net.
Sears was replaced with twenty to go as the U’s tried to shore things up, Eastmond coming on to replace him.
The visitors had another chance to get back into the game when Gilbey caught Judge in the box. But if the Bees thought they could reduce the deficit, Walker thought otherwise as he tipped the ball away from the same corner that he had denied Kevin Lisbie last season.
Ibehre limped off as the game approached injury time, with the U’s having to see out the game with ten men having used all their subs.
Both teams were happy to see out time, though, with the U’s well in control of the game.
And the U's recorded an important win which means the final week of the season should be just as enjoyable.