Chelsea stood firm to see off a late Leicester challenge as the Premier League champions climbed into the top three with a third straight victory.
Both sides struggled to find a finishing touch before Alvaro Morata nodded in Cesar Azpilicueta’s searching pass to put Chelsea ahead before half-time.
The visitors pressed home their advantage after the break as former Foxes midfielder N’Golo Kante, gifted time and space, drilled home low from 30 yards.
A foul by Thibaut Courtois gifted Leicester a penalty that Jamie Vardy converted, sparking Leicester into life in a frenetic final half-hour.
But it was Chelsea substitute Willian who came closest to adding to the scoring with a curling strike just wide of the post.
Leicester, who slip to 17th, have now lost six of their last seven home games against Chelsea.
Chelsea end September blues
Prior to this match, Chelsea had not won a Premier League away fixture in September in any of the last four seasons – but Antonio Conte’s side have put in strong performances at the King Power in recent times.
They started brightly and dominated possession in the opening stages but the visitors’ finishing left something to be desired.
Morata was in the mix throughout the first half but was kept in check by Leicester captain Wes Morgan, who provided two crucial blocks in the box to deny him.
The Spaniard eventually got the best of their personal duel, peeling away from the veteran defender to guide a glancing header beyond Kasper Schmeichel from Azpilicueta’s pinpoint pass.
Kante’s strike against his former club – which Schmeichel, quite rightly, looked annoyed to have allowed past him – should have been the end of the match as a contest, but the visitors seemed to lose focus.
Courtois’ clumsy challenge on Vardy for the penalty handed Craig Shakespeare’s men a lifeline, but they could not use the momentum of that goal to claim an equaliser.
Conte’s introduction of Eden Hazard – returning after an ankle injury – and new signing Davide Zappacosta appeared to steady the visitors.
Zappacosta almost marked his debut with a goal after connecting with Hazard’s cross, but it was fellow substitute Willian who had the best chance late in the game when he fired Hazard’s pass low into Schmeichel’s gloves.