Home boss Charlie Christie rang the changes, with debuts for young Zander Sutherland and goalkeeper Michael Fraser, who ended Mark Brown's 176-game record run in the first team.
Bairns boss John Hughes missed the match due to a family bereavement, with Brian Rice taking on his duties.
Caley Thistle forward Craig Dargo went close with a swerving drive, before Falkirk tested Fraser when Daniel McBreen flashed a low shot goalwards.
The visitors had to take off Kenny Milne after just 16 minutes when he hurt his back in a midfield collision and Craig McPherson replaced him.
Moments later, Caley Thistle shot in front in sensational style.
Russell Duncan, who found himself in space, hit a wonderful 35-yarder high into the top corner to bring the fans to their feet.
That advantage was doubled on the half-hour mark, as the Caley Jags went for their fourth straight victory.
Alan Morgan's corner found its way to the back post and Dargo slammed home an angled drive in style.
After the break, the Bairns' Liam Craig had a dig from the edge of the area, but Fraser held it confidently.
The sides were evenly-matched for long periods, but clear-cut chances were at a premium.
With 20 minutes to go, Morgan let rip from long range, but his shot flashed wide as Caley Thistle went for a killer third.
Alan Gow forced a fine diving save from Fraser late on, but Inverness held on for maximum points.