Guernsey face the 2011 Island Games host, the Isle of Wight, in the final of the men's football after a 3-2 victory over Aland in the semi-finals.
The Sarnians went behind after 16 minutes when Peter Lundberg scored from the spot, but Dominic Heaume equalised just four minutes later.
Two minutes after half time Glyn Dyer put Guernsey ahead from the spot before Lundberg scored a second to level it.
Substitute Ross Allen came on in the 74th minute to score the decider.
In the final minute of normal time Aland's Simon Snickars was sent off after picking up a second yellow card.
Tony Vance, Guernsey's senior coach, said: "Full credit to the boys, in the Muratti we didn't protect our lead well enough but twice now we've managed to close the game off.
"I thought the boys were magnificent, we played when we needed to and mucked in when the time was right.
"A couple of silly mistakes let them back in and made it a nervy finish for us, but all in all I think we deserved the game."
Fellow Channel Islanders Jersey lost 1-0 to the Isle of Wight so they will play off against Aland for the bronze medal.
Guernsey were last in the football final in 2005, when they played the then hosts the Shetland Islands and lost out 2-0.
The Sarnians lost to Jersey in the 2009 semis and did not send a team to the 2007 Games in Rhodes.