The route is operated using an Airbus A321-200, with capacity for 195 passengers in a two-class (economy and business) layout.
The flight leaves Istanbul at 10.50, arriving into Gatwick's North Terminal at 12.50.
From Gatwick, the flight leaves at 13.55 and arrives into Istanbul's Ataturk airport at 19.45.
Turkish Airlines has joined a growing list of carriers launching out of Gatwick, including Air Asia X, Vietnam Airlines, Hong Kong Airlines and Air China.
Guy Stephenson, Gatwick’s chief commercial officer, said: “We are competing with other airports in London and the South East in order to give passengers the greatest choice of destinations to fly to.
“We already offer a choice of over 200 destinations, which is more than any other airport in the UK.”
The Turkish national carrier is the only airline to fly between Gatwick and Istanbul Ataturk Airport.
Easyjet currently operates flights from Gatwick to the Turkish city, but it flies into Istanbul’s Sabiha Gokcen Airport.
Sabiha Gokcen is on the Asian side of Istanbul, 35 km from the city centre, while Ataturk is on the European side and is only 24 km from the city centre.