Signs at Terminal 5 showed customers where to “ChecK-ane” for the 8:45am flight.
Fans were being offered St George’s Cross face painting and boarding passes with customer name “Football” and destination “Home”.
The carrier gave away the Marks and Spencer waistcoats, as worn by England boss Gareth Southgate, to some of the 860 people flying with them to Moscow today.
BA said it had loaded extra champagne and bitter, said to be Southgate’s favourite tipple, on all of its Moscow-bound flights.
Crew on board one flight adapted the usual safety demonstration in honour of the semi-final, holding up scores predicting a 3-0 win. They joked: “If anyone feels overwhelmed by the magnitude of this moment, oxygen will be provided.”
Staff decked the cabin with bunting and chants broke out on the way as customers got into the spirit.
Before the 8:45am departure, customer Will Kumar said: “After the second goal on Saturday I texted my wife and said ‘I’m going’ and that’s when the planning started.
“I can’t go back for the final though. I’ve used up all my credits with my wife.”
Meanwhile, public transport bosses have been showing their support for the Three Lions on buses and trains.
On the Tube, a passenger filmed a train departing from Southgate station, where someone had added “Gareth” above the sign, and he whispered “it’s coming home” as the train pulled away.
In Greater Manchester, Stagecoach buses had “it’s coming home” or “come on England” on the front display.
On the Tyne and Wear Metro system there was the same message on the public displays, although the apostrophe was missing due to a shortage of space for the lettering.
A spokesman for operators Nexus said: “We’ve got football’s coming home messages on all of the information screens at Metro and bus interchanges today to show our support for the England football team in tonight’s World Cup semi-final.
“Fingers crossed they can win tonight and reach the final.
“The whole country is showing its support for the Three Lions and we were determined to play our part.”