The airline will add additional daily flights from the West Midlands airport on Tuesdays and Wednesdays, starting March 31.
Services will depart Birmingham at 10.40am and 5pm, arriving 4.35pm and 10.55pm local time.
Flights will be operated by Boeing 737-800 aircraft.
Tom Screen, Birmingham airport’s acting aviation director, said the move came in response to increasing demand for the route, and would offer passengers greater flexibility.
Omer Faruk Alier, Turkish Airlines’ general manager Birmingham, added the route offered customers connections from Istanbul to more than 300 destinations worldwide.