Gregory Richardson scored the only goal for Joe Public in the 80th minute. The Islanders were shut out after scoring 24 goals in their first four games in Trinidad.
Joe Public will now meet Jamaica's Harbour View in Friday's final. Harbour View beat T&T's San Juan Jabloteh, 10-9, on penalties after their game ended in a 0-0 tie.
The Caribbean tournament will qualify the champion to the 2008 CONCACAF Champions Cup.