An independent jury selected Ms Gao for the $25,000 (pounds 16,000) prize, to be awarded on 3 May, World Press Freedom Day, Unesco said.
Ms Gao, 53, once labelled an "enemy of the people" for her writing, was sentenced in November 1994 to six years in prison for "leaking state secrets". She was first detained in 1989 after the Tiananmen protests and held for 14 months.
Unesco said: "She has paid, and is still paying, with her own freedom for her commitment to media independence."
In 1988, she became deputy editor-in-chief of Economics Weekly, run by dissident intellectuals. According to Unesco, Ms Gao is one of 35 writers and journalists at present in detention in China. AP