© Getty Images
The Magpies should have taken the lead in the ninth minute when the visitors failed to clear their lines from a corner. Moussa Sissoko's ball into the box fell to Fabricio Coloccini, but he put his effort wide.
Leicester responded with an excellent chance of their own as Leonardo Ulloa released the run of Matty James through the middle, but, with only Tim Krul to beat, the midfielder fired an effort straight at the keeper.
The Foxes almost went ahead in fortuitous circumstances when Marc Albrighton raided down the left and whipped a cross to the back post. The ball curled viciously towards goal and beat Krul, but cannoned off the crossbar and went over.
© Getty Images
In the second half, Newcastle went close when Sissoko drove an effort at goal from 20 yards which took a deflection and went narrowly wide of the post, with Kaspar Schmeichel seemingly beaten.
Papiss Cisse somehow failed to put his side ahead in the 52nd minute when he capitalised on a poor back pass by Paul Konchesky and rounded Schmeichel, but he found the side netting with the goal gaping.
Obertan spared Cisse's blushes when he put his side ahead in the 71st minute, as he collected a pass from the striker and beat two challenges before finding the bottom corner for his first league goal in two years.
Leicester upped the ante late in the game and Danny Drinkwater managed to carve out space for himself in the area, but he fired his shot straight at Krul.
The Magpies had the chance to kill the game late on when Ayoze Perez whipped a cross into the box for Cisse, but the striker's header was tipped over the bar by Schmeichel.
Newcastle's defence was resolute as they held out for an important first league win of the campaign.