Ex-BBC journalist Jacky Sutton, 50, is understood to have been found dead in a toilet at the city's Ataturk airport. The circumstances are unclear.
She was the acting Iraq director for the Institute for War and Peace Reporting (IWPR) and had been travelling to Irbil, northern Iraq.
The Foreign Office said it was "providing consular assistance" to her family.
BBC correspondent Ben Ando said Ms Sutton arrived at Ataturk Airport on a flight from London on Saturday and had a two-hour wait for a connecting flight, which she apparently missed.
"Local media are reporting that she didn't have enough money to purchase a replacement ticket and then she was found dead in the toilets a couple of hours later," he added.
"What exactly happened though is not known."
The London-based IWPR supports local journalism in countries affected by conflict and crisis.
Its previous Iraq director Ammar Al Shahbander was killed in a car bomb attack in Baghdad on 2 May and a memorial service was held for him in London last week, according to the IWPR website. Ms Sutton had been in London attending the service.
Executive director Anthony Borden said: "She was extremely bright, highly competent, and well able to handle herself in difficult environments, and she was universally loved. We are in total shock."
Ms Sutton had been studying for a PhD at the Centre for Arab and Islamic Studies at the Australian National University. Her research focused on international development support to female media professionals in Iraq and Afghanistan between 2003 and 2013.
Centre director Prof Amin Saikal said they were "deeply saddened and shocked by the tragic death of one of its brilliant PhD students".
Prof Saikal said: "She was not only an outstanding research scholar, but a highly valued friend and colleague who made remarkable contributions to the work and activities of the centre."
Ms Sutton worked for the BBC World Service between 1998 and 2000, reporting from Africa, the Middle East and London.
She also served in senior roles at the United Nations.
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