Heathrow Airport became the 42nd domestic sponsor of the London 2012 Games today.
It is expected that about 80% of all the people who will travel to the Games will go through the airport. This includes athletes, officials, sponsors, media and spectators.
The deal makes Heathrow London 2012's official host airport.
The "first impression will reflect London 2012 in terms of branding but crucially by providing the warmest of welcomes to the city", London 2012's commercial director Chris Townsend said.
The day after the Olympic closing ceremony - August 13 2012 - is set to be Heathrow's busiest day ever.
About 218,000 bags should leave the airport, compared with 160,000 on the previous busiest day.
Around 15% of the bags will be outsize sporting equipment such as canoes, vaulting poles or bikes, which cannot be processed through normal baggage systems.
Baggage drop facilities at the Olympic village, shipping some baggage as freight, and building a temporary Olympic terminal, which would be taken down after the Games, are some of the options being considered to try to cope with the extra demand.
Heathrow is recruiting 1,000 volunteers - via http://www.teamheathrow.com - from local communities to greet the athletes, VIPs and spectators.
BAA chief executive Colin Matthews described London 2012 as "Heathrow's greatest challenge".
He said: "Every part of the airport is working together so we can give the world's greatest athletes the world's greatest welcome."