Gatwick has submitted plans to the Airports Commission for a second runway to the south of the current site.
The airport's chief executive Stewart Wingate claims the proposal provides "the most affordable, sustainable and deliverable solution" for London and the UK as a whole.
He added that, at an estimated cost of between £5 billion and £9 billion, the runway could be built at "a fraction of the cost of expansion at Heathrow" and could be operational by 2025.
Heathrow unveiled its own expansion plans last week (see online news, July 17) with the promise to deliver extra capacity for between £14 billion and £18 billion.
Proposal: How a second runway at Gatwick might look
Wingate said: "London is the best connected city in the world today because the UK's aviation industry is one of the most competitive and innovative.
"Our proposal to the Airports Commission builds on this foundation and would ensure that the UK has an airports policy which offers the additional capacity that Britain needs, improves the resilience of the airports system and, above all, can be delivered.
"Our evidence shows clearly that an additional runway at Gatwick would best serve the needs of all passengers, and give certainty to airlines, communities and businesses. It would deliver the connectivity the UK needs with lower environmental impacts, whilst spreading the economic benefits.
"A two-runway Gatwick, as part of a constellation of three major airports surrounding London, will also provide flexibility in an industry where the only constant is change."
The Airports Commission, headed by Sir Howard Davies, will now draw up an interim report covering the need for extra capacity and also a shortlist of potential options and sites.
This report is due to be published by the end of the year, although final recommendations will not be made until after the next general election in the summer of 2015.