The Saints went ahead after nine minutes when Lee Dickson touched down, with Ryan Lamb kicking the extras.
Sarries got on the scoresheet three minutes later when Owen Farrell kicked over a penalty.
However, the hosts went into overdrive soon after with Lamb kicking a penalty of his own before tries from George Pisi and Phil Dowson stretched the lead. Those scores, combined with a drop goal from Lamb, made the score 27-3 at the break.
Both sides managed to cancel each other out after the interval, but Lamb kicked over another penalty just before the hour to make it 30-3 to the home side.
Ernst Joubert touched down in the corner right at the death, but it was only a consolation for the visitors.