It was Wallwork's first goal for 19 months and only his second in 99 games since his arrival on a free transfer from Manchester United in the summer of 2002.
The midfielder's 41st-minute drive ultimately set the seal on the win for Albion who took control when Nathan Ellington converted an 11th-minute penalty.
Albion have now won their opening two home games - underlying their ambition to make The Hawthorns a fortress as they seek an instant return to the Premiership.
But, while the Baggies aim to bounce back into the top-flight, Colchester look destined to struggle to avoid an instant return to League One.
No-one can doubt their hard work but the bare facts are that they remain pointless after four games of their first taste of life in the Championship.
They produced a committed display and substitute Jamie Guy gave them hope of salvaging something from the game when he scored with his first touch after 83 minutes, but a lack of firepower threatens to be their undoing as they slipped to a fourth one goal defeat.
Albion started at a rapid rate and it was a surprise it took them 11 minutes to break the deadlock.
Before Ellington pounced he dragged a shot wide and was denied by U's goalkeeper Aidan Davison, while John Hartson had a header cleared off the line by Kevin Watson.
The hosts' intense pressure had to tell eventually and it did when Hartson was fouled by Wayne Brown. Referee Paul Taylor had no hesitation in pointing to the spot and Ellington sent Davison the wrong way with his penalty.
Davison denied Paul Robinson with a smart save in the 29th minute but he only delayed the inevitable temporarily before Wallwork doubled Albion's advantage.
Wallwork stabbed his shot beyond Davison's right hand following good build-up play involving Nigel Quashie and Steve Watson.
Albion were content to hold on to what they had and that allowed Colchester to come back into the game and grow in confidence.
Richard Garcia was unfortunate not to reduce the arrears at the start of the second half when he was denied by Pascal Zuberbuhler and Garry Richards had a shot deflected over the bar.
Guy then set up a tense finale when he volleyed Watson's pass home from six yards but it was too little too late for a game Colchester side.