They were forced to defend for long spells of the first-half but whatever Terry Butcher said to his men at half-time clearly worked the oracle with three goals inside 15 minutes killing the game off.
Although the opening half finished goalless, it was not for the want of trying from both teams with Caley keeper Dean Brill making a decent save to deny Gary Harkins inside the opening 10 minutes.
St Mirren continued to press and came closest to breaking the deadlock on 31 when Jim Goodwin smashed a 25-yard free-kick against the post.
But it was the home side who took the lead a couple of minutes after the interval when David van Zanten was adjudged to have handled in the box and James Vincent scored from the spot to mark his Caley debut.
Worse was to follow about 60 seconds later when a poor back pass from Danny Grainger put keeper David Cornell in trouble and Aaron Doran stole in to make it 2-0.
The points were secured for Inverness on the hour, Caley ending a dominant 15-minute spell when last season's leading scorer Billy McKay glanced a header past Cornell from the edge of the six-yard box.
As if things were not bad enough for the visitors, Van Zanten was shown a red card with eight minutes left on the clock for a professional foul.
Thomas Riley did come close to a consolation goal for St Mirren in the closing seconds but Brill was equal to his effort and ensured a clean sheet as well as three points on a most enjoyable opening day for Caley's supporters.