The carrier has described Iran as "an important destination"
British Airways has resumed direct flights to Iran after a nearly four year suspension following the lifting of sanctions on the country.
Describing Tehran as "an important destination" for the airline, BA will operate six return flights per week between London's Heathrow Airport and the Iranian capital, rising to a daily service later this year.
The service was suspended in October 2012 amid instability in the Middle Eastern country.
In January, sanctions were lifted against Iran after the international nuclear watchdog said the Tehran government had met all its obligations under a deal with six world powers.
The first BA flight to Iran, a Boeing 777, will depart from Heathrow on Thursday at 9.10pm.
Flights had been expected to resume in July, but were delayed while the route was established.
A spokeswoman for BA said: "The Iranians have been extremely helpful in setting up this important new route and have been as keen as we are for the service to start.
"Tehran is an important destination for British Airways and we wanted to ensure that the service we offered met the highest standards our customers rightly expect of us from day one."
Sean Doyle, British Airways' head of network and fleet, said: "The recent lifting of sanctions has also effectively allowed Iran to re-open for business and paved the way for commerce to re-connect with Iran's economy, which is the second largest in Middle East and North Africa, with a diverse range of businesses and industries."
The service will be operated by a Boeing 777 with return fares starting from stg£535 (€635).
Air France resumed flights between Paris and Tehran in April after an eight year hiatus.