The game had the feel of a pre-season encounter early on as the autumn sunshine seemed to lull everyone into a false sense of security.
There was little to show in front of goal in the opening 25 minutes apart from a Craig Dargo volley and a Calum Elliot shot which failed to trouble the keepers.
Inverness took the lead on 25 minutes when Graeme Smith could only punch a Barry Wilson free-kick on to the head of Ross Tokely and the defender coolly placed the ball past Mark Reynolds.
Ten minutes before the break it took a fine save from Mark Brown to stop Well equalising when he somehow tipped a Brian Kerr free-kick over the bar.
Well survived a scare at the other end as the half came to a close when Smith saved a Wilson angled drive but Graham Bayne dallied on the rebound and his attempt was blocked.
After a decent early penalty shout for Well when Tokely felled Scott McDonald, the home side fell two down when Wilson robbed Paul Quinn before squaring for Dargo to slide home with the easiest of chances.
With 19 minutes left Motherwell snatched a lifeline as McDonald halved the lead when he neatly headed home a Keith Lasley free-kick from the right.
But the fight back was short lived as Inverness sealed the win with a third with 11 minutes left as Bayne cleverly flicked on a Wilson corner for Grant Munro to rifle high into the net.
Things went from bad to worse for the home side as the Highlanders made it four with two minutes left as Rory McAllister rose unmarked to head a cross high into the roof of the net.