The twice-weekly service to the Turkish capital will operate on Wednesdays and Saturdays.
Umit Yalcin, the Turkish ambassador to London, joined crew at Gatwick to mark the occasion.
Celal Baykal, Turkish Airlines general manager London, said: “This new route is being launched in direct response to increased demand from our customers across the country, and is further evidence of our commitment to exceeding passenger needs.
“We look forward to welcoming people from across the UK on our new route and keeping widen their world with Turkish Airlines.”
