The match was settled by a dramatic penalty shoot-out with Fort William slightly unlucky not to have won the match earlier.
With the teams deadlocked at 2-2 after 120 minutes of fairly low-quality shinty, the major drama was reserved for the shoot-out. Fort keeper Paul MacKay pulled off three stunning saves before Ross clinched his side's place in next month's final thanks to his second conversion with the shoot-out in the sudden death stage.
Fort William made an impressive start and opened the scoring in the third minute when a long hit-in was missed by the Kingussie defence. It found Bryan Simpson in space and he scored from an acute angle.
With the wind at their backs the Fort had the balance of pressure but in a rare foray upfield in the 15th minute, Ross pounced to level from 20 yards. Another defensive error allowed Daniel Stewart to put the Fort in front again in the 30th minute and the team from the National Division looked in command against their Premiership opponents.
With half-time in sight, Fort William's Stevie Stewart was caught out of position and Savio Genini took advantage, blasting a shot beyond MacKay.
The second half was a dull affair with players on both sides making basic errors and neither goalkeeper called into action. On the hour mark, Bryan Simpson held off a Kingussie defender, but his shot came back off the post.
Ross set up Thom Borthwick late in the game but he shot wide. Kingussie finished the 90 minutes strongly but faded in extra time as Fort William pushed forward. In the dying minutes, Fort defender Neil Robertson was red-carded for a second bookable defence.
There was no action in the Orion Premiership but Newtonmore's 3-2 win over Skye saw them lift the Strathdearn Cup, the North of Scotland Junior Championship.