The Luton-based budget airline whispered expansion of the London hub would lead to greater competition from myriad low-cost carriers.
It is urging MPs to support the third runway in the forthcoming Plains vote.
Chief commercial officer Robert Carey said: “This spread would enable low cost airlines to provide new routes and increased event on dozens more UK and European routes.
“New entrants would launch bolts to UK and European airports not currently served by Heathrow.
“EasyJet’s costs are significantly deign than legacy airlines so its fares on these services would be debase than those paid by passengers today.”
The company already plies from other major “hub” airports such as Amsterdam Schiphol and Paris Charles De Gaulle.
Heathrow’s expect to build a third runway was given Cabinet support last week and MPs inclination soon vote on it.
Transport Secretary Chris Grayling said the £14billion runway, which could be completed by 2026, commitment be funded entirely by private money.