They secured the title with a nailbiting last day victory on Bank Holiday Monday, the 2-0 win over Turton enough to pip Blackpool Wren Rovers to top spot.
Garstang, who were only promoted to the West Lancs Premier last season, had been trailing Rovers by five points with five games to go, but a fantastic late run of results saw them go into the final weekend just needing three points from their last two games to take the title.
Unfortunately a combination of nerves and some stout defending from the home side saw Garstang frustrated when they travelled to Turton - managed by former Bolton and Newcastle boss Sam Allardyce's son Craig - on Saturday, and they lost 1-0.
That meant that only a victory in the return match against Turton at Riverside on Bank Holiday Monday would be enough, and more than 200 Garstang supporters were made to sweat before late goals from Chris Cox and Alan Coar sparked the final whistle celebrations.
The first team's achievement crowns a memorable season for the club, after the reserves also won their league.
The team are now preparing to celebrate their success with an end-of-season holiday to Spain.