In what was an instantly forgettable opening half, Motherwell took the lead with the game's first real chance.
Ross McCormack's 15th-minute corner was flicked on at the front post by Stephen Craigan and an unmarked David Clarkson had plenty of time to divert the ball into the net from close range.
The visitors were offering more of a threat in the final third, but could not turn their possession into goals.
In stark contrast, Caley Thistle were making very little impact as an attacking force and it took them until the 38th minute to register a shot of any note, Russell Duncan with an effort that flew high over the crossbar.
It did, however, spark Inverness to life and two minute later they went significantly closer. A Don Cowie free-kick was touched on by Graham Bayne and Grant Munro stole a march on his marker, but could only send his effort into the side-netting.
Caley Thistle were now beginning to create opportunities and Duncan should perhaps have done better 60 seconds later when he was played in by Dennis Wyness only to drive a low shot inches wide of Graeme Smith's goal.
It offered the home side some encouragement going into the second half, but Inverness contributed to their own demise as Graham Bayne's late challenge from behind on Clarkson after 49 minutes resulted in the forward being given his marching orders for a second bookable offence.
Only four minutes later Motherwell made full use of their numerical advantage with McCormack driving to the goal-line and setting up Clarkson who, despite having his initial effort blocked by Chris Porter, fired the rebound into the roof of the net.
Caley Thistle's woes continued as Ross Tokely was shown a straight red on 62 minutes for a late challenge on Steven McGarry, effectively ending any hope they had of getting something from the game.
Motherwell were content to play out time, although they did add a third goal three minutes from the end when Clarkson played in substitute Darren Smith, who calmly slotted the ball under Inverness goalkeeper Michael Fraser to complete the scoring.