A win in the Highlands would have taken Dundee United top of the league.
But despite a promising start for Jackie McNamara’s men, that never looked like happening.
The home team dealt better with the windy conditions and were good value for the three points, secured by a first half strike from Marley Watkins.
Just over 60 seconds into the game Chris Erskine had a decent chance on the angle but he skied his effort over the bar.
The same player came closer to breaking the deadlock five minutes later when he again found a good position in the box, was picked out by Ryan Dow, and struck the base of the post with his shot.
The ball rebounded back on to Dean Brill and could quite easily have gone off him into the net, but the keeper’s luck was in.
United had made the better start but that counted for nothing when Inverness took the lead with their first attack of the game on 11 minutes.
Greg Tansey sent in a low cross from the right and Watkins gave Rado Cierzniak no chance by redirecting it past him from eight yards out.
Good United penalty box defending stopped Caley Thistle from doubling their lead twice within two minutes around the half-hour mark.
First Sean Dillon got his head to a goal-bound Danny Williams shot and then John Rankin cleared a Josh Meekings header off the line.
United had barely been in the ICT box since the early stages but they should have equalised just before the break. Callum Morris had a free header from a corner but couldn’t keep it down.
There was a time when Billy McKay was the most lethal finisher in Scotland. Not anymore.
On 53 minutes the Englishman was one-on-one with Cierzniak through the middle, but the composure of last season was nowhere to be seen when he scuffed his shot straight at the United keeper.
McKay had another more difficult chance on the hour. The connection was better this time but his volley from eight yards went straight into Morris.
In 69 minutes United out-muscled his marker. He couldn’t follow it up with something more subtle was though, as his attempted lob missing the target.
Morris was indecisive on the edge of the box and let James Vincent in on goal. Just as McKay couldn’t take advantage of a glorious chance earlier, Vincent too was wasteful.
United weren’t able to put together any late pressure and ICT saw the game out comfortably.