The three points from this win helped United SC climb up the standings to share the lead with JCT with six points each, while Mumbai FC remained on the bottom without any point, in stark contrast to the way they started their campaign in the last season.
The Subrata Bhattacharya-coached side dominated right from the start in the flood-lit venue as Edmilson scored two goals in the seventh and 14th minutes to give United an unassailable 2-0 lead.
A penalty conversion by their Japanese import Kayne Vincent came to the rescue of Mumbai FC who were terribly off-colour in the first-half and appeared a tad more cohesive during the second-half.
Brazilian enfant terrible Edmilson was dumped by East Bengal for his antics against coach Subhas Bhowmick and teammate Saumik Dey there, but with three goals from two matches today he became the leading scorer.
Edmilson, who is very much instrumental in their team's good show this season, also picked the Man-of-the-Match trophy.
Reeling under a huge player exodus and also their coach David Booth and manager Henry Menezes, Mumbai FC are a shadow of their last season's team when they got off to a flier beating Mohun Bagan, East Bengal and Mahindra United in three consecutive wins in 2008-09.
With their forward line-up banking on Rakesh Yadav and Vincent, they failed to score as United SC dominated most part of the game.
The combination of medio Jayanta and Edmilson gave result for United SC in the seventh minute. A nice through from Jayanta was brilliantly taken up by Edmilson who stroked the ball into the Mumbai net to give a 1-0 lead.
United soon made it 2-0 after a huge lapse by Mumbai custodian Amit Singha Roy who failed to hold on to an Edmilson shot.
A well positioned Roy tried to grab the Edmilson long ranger with both hands but the powerful shot went into the net after kissing the goalkeeper's hands as the Brazilian went euphoric.
After going 2-0 in the 14th minute, United appeared in a complacent mood but the Mumbai boys failed to convert their chances even as they appeared a bit more aggressive in the second-half.
United stopper Kingshuk Debnath brought Mumbai's Yadav down inside the box after elbowing from behind to be awarded a penalty which was converted by Vincent.
But the Mumbai boys did not yield any goal futher to see the side go down.
United SC on the other hand would be cursing their luck missing a golden chance in the 46th minute. In a goalmouth action, Edmilson and Shylo Malswam Tulunga missed it narrowly with their shot hitting the crossbar and finally saved by Mumbai FC.
United SC suffered a jolt in the form of their Brazilian defender Eduardo (Du) who sustained a nose injury after a tackle with Yadav early into the match.