BA stopped flying to the country after a bombing in the capital city of Islamabad in 2008, which killed more than 50 people.
But the airline is now scheduled to fly three times a week to Islamabad from London Heathrow on Boeing 787s.
It is the only western airline to serve Pakistan.
In September 2008, a bomb was detonated in a dumper truck outside the Marriott Hotel in Islamabad.
More than 250 people were injured and 54 were killed in the blast.
Shortly after the explosion, BA suspended all flights, declaring: “We will not compromise on the safety of our customers, staff or planes.”
But in December last year, the airline said it would restart flights to Pakistan’s capital.
A new airport was opened in Islamabad in 2018, which has eased concerns about both security and congestion.
Until Sunday, Pakistan’s PIA was the only airline to run direct flights from Pakistan to the UK.
British High Commissioner to Pakistan, Thomas Drew, said BA was joining “an increasing number of British companies doing business in Pakistan”.
