Easyjet has said fares would drop by around a third if Heathrow is given the green light to expand.
The budget airline said the contentious expansion of the airport would allow low-cost carriers to enter the airport for the first time, resulting in increased competition that would drive down fares for passengers.
While also allowing healthy competition, the airline said new entrants would be able to fly passengers to European airports not currently served by Heathrow and heighten its status as a hub airport.
Urging MPs to vote for the third runway, Easyjet's chief commercial and strategy officer Robert Carey said: “Easyjet supported the Airports Commission’s clear and unanimous recommendation and agrees that expansion at Heathrow will provide the greatest passenger and economic benefits, including lower fares by opening up the airport to increased competition.
"Easyjet's costs are significantly lower than legacy airlines so Easyjet's fares on these services would be lower than those paid by passengers today.
“Expansion at Heathrow will bring significant economic benefits to all of the UK and that’s why we urge MPs to support the government’s national planning statement so that work can start to increase the aviation capacity for the UK. ”
Easyjet has always been supportive of a third runway at Heathrow, in contrast to IAG, the owner of British Airways, whose boss Willie Walsh has aired concerns that the third runway will lead to a surge in airport charges that would be footed by passengers.
British Airways is Heathrow’s biggest customer, and Walsh has previously said he wants a full breakdown of costs on expansion as costs on Heathrow projects “frequently increase substantially from their original budget without any justification”.
Heathrow expansion is currently projected to cost £14bn. Earlier this year the airport launched a consultation that shaved off £2.5bn from the overall costs.
The third runway is due to be voted on by MPs in a few weeks' time after it was given the all clear as government policy by the Cabinet earlier this week.
However, many MPs remain opposed to the third runway. Labour appears ready to instruct its MPs to block the plans because the government's statement did not pass Labour's four tests, which are: any expansion must meet the UK’s capacity demands; noise and air pollution obligations are not breached; the UK is still able to meet its climate change targets in their entirety, and that the runway will support growth across the whole country.