Cardiff City advanced to the second round of the Carling Cup with a professional performance at Layer Road.
Cameron Jerome struck his third goal in three games
Mark Yeates missed an early gilt-edged chance from eight yards for Colchester, then on the half hour Jeff Whitley was brought down in the box by Kemal Izzet.
Darren Purse sent Dean Gerken the wrong way with a fine right-footed penalty.
Willie Boland then won the ball and freed Alan Lee. The striker went on a strong run and fed Cameron Jerome, who rounded Gerken to seal the victory.
Colchester enjoyed some pressure in the second half, but they never seriously threatened Neil Alexander's goal.
The only sour note of the night for the Bluebirds was an injury to left-back Chris Barker.
He hobbled off before half-time and is considered doubtful for Saturday's game with Wolverhampton at Ninian Park.
Colchester boss Phil Parkinson:
"I have no complaints about the penalty. Pat Baldwin fouled Jeff Whitley and it looked like one from my position.
"I'm disappointed that we didn't get going, we looked very flat.
"We got the ball into the final third but we were just not strong enough.
"We weren't strong enough at the back either. It gives me a lot of food for thought."
Cardiff assistant boss Terry Burton:
"This was a potential banana skin for us.
"We have had a lot of players come in over the summer and we are still trying to gel them together.
"But it was a good performance tonight and, most importantly for us, it was a good team performance."
Colchester: Gerken, Stockley (Williams 45), Baldwin (Elokobi 78), Chilvers, Brown, Danns, Watson (Howell 78), Izzet, Yeates, Iwelumo, Halford.
Subs Not Used: Cousins, Guy.
Cardiff: Alexander, Weston, Loovens, Purse, Barker (Parry 45), Boland, Whitley, Koumas, Cooper, Jerome (Ferretti 84), Lee.
Subs Not Used: Margetson, Mulryne, Cox.
Goals: Purse 31 pen, Jerome 34.
Ref: R Beeby (Northamptonshire).