Dempo emerged champions in the 11th National Football League with a match to spare, after defending champions Mahindra United went down 1-2 to East Bengal in a 17th round match in Kolkata on Tuesday.
The Goa team's triumph is the second in three years, having also won the crown in 2005.
Mahindra, with 27 points from 17 matches, cannot now overhaul Dempo's tally of 33 points in 17 matches. JCT, with 28 from as many matches, are placed second in the league. [See League table].
East Bengal fought back from a goal down to dash Mahindra United's chances of defending their title.
The Mumbai side was leading 1-0 at half-time through a 28th minute strike from Andrews Mensah.
But man of the match Boniface Ambani scored twice in the space of seven minutes right at the start of the second half to give the Kolkata giants victory.