Post William beat Nairn County 5-2 on Wednesday in a North of Scotland Cup conflict.
Their last triumph was in April 2017 when they vanquished Strathspey Thistle 4-1.
The club tweeted: "Mind boggling stuff. An incredible night at Claggan Park this evening. A unimaginable inclination. We might want to thank everybody who went along.
"What's more, we might want to thank everybody on the web, the world over who have celebrated with us. Your help doesn't go unnoticed."
Jack Brown and Donald Morrison were among the goalscorers for The Fort, who are overseen by Russell MacMorran.
Nine credit signings from Scottish Championship side Inverness have helped Fort William, whose losing streak highlighted in an ongoing BBC Scotland narrative.
The group were saluted by clubs the nation over, just as by the SNP's Westminster chief Ian Blackford.
Mr Blackford expressed: "Ardent congrats on an insistent triumph following a 840-day pause.
"An extraordinary story of constancy and devotion.
"Regardless of how frequently they got thumped down, they cleaned themselves down and went once more. Good karma pushing ahead!"