It was reported in Turkish media that Ryan fell from the fifth storey of a building while staying at a friend's house.
TRT World - where Ryan worked - said the pair had retired for the day to separate rooms.
The friend was awoken at 2.20am by a noise and discovered an open window and Ryan on the ground below.
Police were investigating the death, which was described as "suspicious".
A Ministry of Foreign Affairs and Trade spokesperson said the ministry was aware of the death of a New Zealander in Istanbul and was providing consular assistance to the family.
Ryan, 34, was a freelance journalist who had previously worked for Al Jazeera and The New York Times.
Asfaaq Carim wrote on TRT World his "dear friend" left behind "a rich legacy of stories that have left a deep impact on people and journalists".
"Her work was tough on power and was decidedly empathetic to all sides," he wrote.
"What made Yasmine stand out, in a newsroom full of talented journalists, was her resolute commitment to listen. To listen sincerely and deeply."
The intrepid career woman was credited with being the first English-language journalist to start in-depth reporting on events in Tunisia preceding the Arab Spring.
New Zealand-born Al Jazeera news anchor Kamahl Santamaria described her as a Kiwi doing great work in the world with a legacy that would not be forgotten.
Her LinkedIn profile describes her as an award-winning digital, print, television and video journalist with over a decade of experience with top international news outlets.
She was a 2016 World Press Institute Fellow and was more recently a senior features editor at TRT World in Istanbul.