The goal-shy Pars travelled north with a depleted squad, especially in the forward area, where their problems have mainly lay this year.
The Highlanders, meanwhile, were seeking their first home league win since they saw off relegated Dundee back in April.
The Inverness side got off to a cracking start when Ian Black fired a stunning 20-yarder high into the roof of the net after superb link-up work from Barry Wilson and player-boss Craig Brewster. That was the former Blackburn Rovers man's first competitive goal for the club.
Then it was doubled to 2-0 after nine minutes when young David Proctor tucked home a spilled ball by keeper Allan McGregor from Wilson's low drive.
Dunfermline struggled to find a way into the game, and some haphazard defending left them looking exposed against their confident hosts.
Brewster almost grabbed the third goal, but McGregor did well to deal with his header.
So the Pars went in still two goals down at the break with lots of talking to do by manager Jim Leishman.
Moments after the break, Proctor flashed a header just past the right post from a Richard Hastings cross. Wilson sent in an inviting corner and Craig Dargo knocked a header off the bar as Caley Jags went for the killer goal on 68 minutes.
Out of the blue the Fifers then grabbed an unlikely lifeline when Lee Makel smashed home an unstoppable drive from 20 yards to make for an uneasy ending for the Inverness men.
A stoppage-time Russell Duncan goal for Inverness, however, was chalked off for offside, and it finished 2-1.