He warned that "so many people want to come to London, but don't because they struggle with the visa regime".
Walsh, who runs IAG, the airline group which owns BA, added, "It's so much easier for them to go elsewhere. London is losing out because of the visa regime."
"We understand the UK has to have strong borders, but you need better systems in place for business people who want to travel here and tourists who want to visit here. People want to experience London, in part because of what they saw during the Olympics," he said.
"It's Chinese tourists particularly who find it difficult to come to the UK," he told the Evening Standard.
Also Read
"They are still coming, and that shows how strong the number of visitors could be, as the Chinese going through the difficulties of travelling here. But if it was easier we'd see a massive increase in tourists from China - and that would benefit the economy," Walsh said.
BA's capacity meanwhile increased by 2 per cent after the introduction of the Airbus A380 and Boeing 787 into the airline's fleet.