Truro City will play in the Blue Square South next season after clinching their fifth promotion in six seasons with a 3-0 win over Banbury United.
The result puts City in an unassailable position at the top of the Southern Premier League with one game remaining.
Les Afful opened the scoring for Truro in the 19th minute, latching onto a Barry Hayles flick.
Hayles then scored the second, with Andy Wakins grabbing a third late-on to the delight of the visiting fans.
Truro end their season against Weymouth at Treyew Road on Easter Monday, where they will be presented with the Southern Premier League trophy.
Manager Lee Hodges told BBC Radio Cornwall: "It's a great way to finish the season, to be crowned champions with a game to go is a fantastic achievement by everyone at the club.
"The fans have been brilliant, when you're sitting there watching the game and you can hear the fans shouting everyone's name, it's fantastic.
"The boys have been brilliant and I love working with them - they're a great set of lads and this is a great place to be at the moment."