Matt Powell and Thomas Lombard were the Worcester try-scorers, and Tommy Hayes added two penalties at a soggy Sixways.
Hayes' first kick was after just two minutes, Irish forced offside after a blistering start from the Warriors, who were still smarting from the fifty-point drubbing at Leicester last week.
Powell controlled the game ably and intelligently with both hand and boot thereafter, and Worcester were much the better team in the first quarter.
The Exiles managed to level things with a Mark Mapletoft penalty, but Hayes responded in kind three minutes later.
Finally Worcester got the breakthrough their superiority deserved after 25 minutes. Powell charged down an attempted clearance by Michael Horak, and pounced on the bouncing ball to take Worcester to an 11-3 lead, which they held until the break.
Riled by the try, Irish responded with a number of attacks, but the Warriors held out doggedly, even with Tim Collier in the sin-bin for the final minutes of the first half after he had pulled down his opponent in the line-out.
With five minutes of the second half elapsed, Exiles' coach Gary Gold substituted his half-backs, bringing on Barry Everitt and Darren Edwards for Mark Mapletoft and Paul Hodgson.
The move worked to some extent, with Everitt slotting another penalty for the Exiles just before the hour, but with Collier back, Worcester were still on top of the game.
The Warriors had the upper hand in the scrum and line-out and from one line-out steal, they took full advantage.
Brad MacLeod-Henderson rose highest on 58 minutes to snaffle possession, and two minutes later Lombard finished off a patient build-up to bring the Sixways sell-out crowd to their feet once more.
For Worcester: Tries: Powell, LombardPens: Hayes 2
For London Irish:Pens: Mapletoft, Everitt