There was much at stake at Fir Park with the hosts starting the day in third spot, breathing down the neck of their second-placed visitors who were desperate for a first victory in six matches in all competitions.
And Well didn't disappoint with a rampant second half display earning the spoils to help them leap-frog their opponents and it was their star man Higdon causing much of the damage.
The 29-year-old had already nodded a Stevie Hammell free-kick onto the roof of the net, but on the half-hour his decisive intervention arrived.
Bizarrely, the striker had just diverted wide a shot from team-mate Nicky Law but swiftly made amends by tapping in the opener after a fluffed cross by Henrik Ojamaa for his 17th of the season.
Caledonian Thistle were not without their chances though in the first period as Andrew Shinnie had one shot saved by Darren Randolph, while another ended up in the net but was ruled out for offside.
Terry Butcher's men continued to look dangerous as defender David Raven surged forward to set up Aaron Doran, only for the lively midfielder to smash the ball narrowly over from 15 yards.
Just before the break, keeper Ryan Esson had to be alert again to keep out Motherwell - firstly from a lame effort by Kallum Higginbotham and then he blocked a savage strike by Ojamaa.
Inverness came out in the second half looking fired up and immediately went close to an equaliser as midfielder Nick Ross darted behind the defence before lobbing his shot way over the bar.
And they'll be regretting their wastefulness, as Law pounced from a goalmouth scramble for his team's second. He initially missed the ball and was lucky enough to have another stab at the ball to poke in.
And just four minutes later, the magnificent Higdon was on target again to bury any thoughts of an Inverness comeback with a stunning volley - it was his sixth goal against the same opponents in three games.
The sound of woodwork dominated the final minutes. Firstly, the impressive Shinnie danced between two defenders for Inverness and crashed a shot from the edge of the box against the post.
And in the closing minutes, Motherwell were a whisker away from a fourth as Law's swerving effort from 20 yards smashed off the bar.