The airport has just released a new poll of 130 MPs by ComRes, which recorded 74 per cent of MPs backing the third runway; a rise of seven percentage points since the last poll in August.
That was done ahead of the government's announcement that Heathrow had received the go-ahead, which Chris Grayling revealed in October.
Since the confirmation of the government's decision, there has been a jump in Conservative support. In the weighted data to reflect the House of Commons makeup, 80 per cent of Conservative MPs said they'd vote for a third runway at Heathrow - up from 71 per cent in August.
Three quarters of Labour MPs also backed the major infrastructure development.
Heathrow chief executive, John Holland-Kaye, said: "Heathrow expansion has more political support than ever before because MPs understand that a third Heathrow runway equips our country with the tools we need to thrive in the 21st century."
The long-awaited decision was announced by transport secretary in October, where he said Heathrow was backed as the government felt "it delivers the greatest economic and strategic benefits to our economy".
The proposed expansion has faced criticism from MPs, some environmental groups and local councils though. A group of councils has banded together to launch a legal challenge, making a submission to the High Court and arguing the government has failed to recognise the expansion's air quality impact. The councils say it will breach laws.
Mayor Sadiq Khan has said he will support the challenge, having directed Transport for London (TfL) to provide advice and assistance to affected borough councils, including Hillingdon, Richmond, Wandsworth and Windsor and Maidenhead.