Crawley top scorer Billy Clarke hit his ninth goal of the season to help beat struggling Colchester for Town's first home league win in nine weeks.
Defender Mark Connolly fired Crawley ahead from close range on five minutes, after U's keeper Mark Cousins had only parried Josh Simpson's header.
Clarke then latched on to Cousins's hurried clearance to fire into the top corner against his old side.
Nicky Adams's clever chip from 18 yards two minutes from time sealed victory.
VIEW FROM THE DRESSING ROOM
Crawley Town assistant manager Anthony Williams told BBC Sussex:
"It was a difficult game. We started well, but they're a good side and they can play a bit of football. It's a difficult pitch to play on but we stuck in there.
"I think sometimes you've got to ride your luck and I think we did that in the second half.
"It was a good team performance and the pleasing thing is they worked hard for each other and got their rewards."
Colchester United manager Joe Dunne told BBC Essex:
"Three-nil is a bad result. I didn't think it was a 3-0 game.
"I thought there were a lot of positives but we started the year how we finished it, which is not what we wanted.
"I could take a tape recorder into the dressing room and just press play because I'm saying the same things again and again.
"We do work at it. We've talked about things and unfortunately you've seen sloppy goals again."