The Guernsey Senior County League beat the Liverpool County Premier League 5-2 to win the FA National League System Cup final at the Track on Saturday.
Goals from Glyn Dyer, Dave Rihoy, Dominic Heaume, Matt Drillot and Ross Allen were answered by only two by David Cooney.
Guernsey now will travel to Croatia to face the hosts own amateur champions and those of Turkey and Wales.
That tournament will be the start of their Uefa Regions Cup campaign.
The visiting side went ahead but Guernsey led 2-1 at half time after goals from Dyer and a great set-piece corner strike from Rihoy.
After a slow restart from the home side, Cooney scored his second to level the match.
It's the biggest prize in amateur football and we're there - it's unbelievable
Guernsey captain Sam Cochrane
The deadlock was then broken by Heaume and was followed by substitute Drillot slotting the ball home and Allen producing a beautiful floating lob to seal the victory.
Guernsey Senior County League and Guernsey national side manager Tony Vance said: "They were just absolutely magnificent.
"Players win matches and they were absolutely superb today, I'm so proud of them, we dug in just when we thought it might have slipped away.
"We deserved to win the game, I'm convinced of that, so we're national champions now and that's fantastic."
Captain Sam Cochrane said: "We've had a brilliant journey in this tournament, we've played really well.
"Our style of football is changing we're very attacking and being like that we do open ourselves up to concede goals, but there's so much belief we're going to score goals we're not worried about that and it showed tonight.
"It's the biggest prize in amateur football and we're there - it's unbelievable."
"The information we get on each team is spot on. We knew the system they played, we knew most of their players, their weaknesses, their strengths and it's worked in every round.
"The homework they do on all these sides is unbelievable and the set pieces Vance gives us to do have won us games and it's fantastic."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.