Thousands of residents, politicians and environmentalists have pledged to resist plans to extend Heathrow.
Some 3,000 people attended the rally at Methodist Central Hall
Organisers said 3,000 people attended a meeting at Methodist Central Hall in Westminster.
Lib Dem leader Nick Clegg was among the speakers from all three major political parties who voiced their opposition.
He said "no, no, no" to plans for a third runway and a sixth terminal. Earlier, Greenpeace activists staged a protest at the airport.
Among proposals for the airport are a 2,200m third runway built north of Heathrow by 2020, with a sixth terminal, which will require the destruction of an entire village.
Critics have said more than 50 communities and towns will suffer increased noise.
Mr Clegg asked the Westminster meeting: "Where is the box that simply says no, no, no?
"Illness, stress, congestion, climate change - how can the government claim that these add up to a good idea?
"They add up to a disaster and it's got to be stopped."
Shadow environment secretary Peter Ainsworth and John McDonnell, the Labour MP for Hayes and Harlington, which borders Heathrow, also addressed the audience.
Mr McDonnell said: "They keep coming and they will keep coming until we stop them now.
"This is my community they are coming for... they want to put a road through our cemetery. They expect us to dig up our dead."
The three main party candidates for London mayor were also heard at the meeting, Lib Dem Brian Paddick in person and Tory Boris Johnson and current Labour mayor Ken Livingstone via recorded messages.
Mr Livingstone said: "There is no case whatsoever for expansion of Heathrow Airport.
"What we want to see is no further increase in air travel at all, quite frankly."
The rally was organised by Heathrow residents' group Hacan Clear Skies and No TRAG (No Third Runway Action Group) and supported by 14 councils in the Heathrow area.
But earlier on Monday, the expansion plans were backed by a borough council which is next to the airport on the Surrey/London border.
Spelthorne has gained from improved transport links, quality housing and commercial benefits because of the airport, members heard at a meeting.
'Heathrow is full'
A spokesman for Heathrow airport said: "Heathrow is hugely important to the UK and London economies - it supports jobs and business - providing our only air link to many long-haul destinations.
"However, Heathrow is full with its two runways operating at 99% of permitted capacity.
"A third runway will not go ahead unless there is no more noise overall than in 2002, unless air quality is better than today, and unless there are improvements to public transport.
"This is not growth at any cost, this is growth within strict environmental limits."
In the Greenpeace protest, four people were arrested after security was breached and a banner about climate change was unfurled from the top of a British Airways Airbus A320, which had arrived from Manchester.