The artist was known for racy nude shots of his friends in which genders blur and limbs intertwine.
His gallery, Hong Kong-based Blindspot, confirmed the death to AFP.
Born 1987 in Changchun city of northeastern Jilin province, the Beijing-based, self-taught artist gained recognition abroad even while his work was censored at home, where the ruling Communist party bans what it deems "pornographic".
Ren had long grappled with depression, a struggle that he chronicled in poetry and prose online.
"Every year, the wish I make is the same: to die earlier," he said in one of his final Weibo posts, published last month on the eve of the Chinese lunar new year.
”For so many years I have been trying to cure myself, splitting my one self into the two roles of doctor and patient," he wrote on his website last summer.
"If life is a bottomless abyss, when I jump, the endless fall will also be a form of flight."
Reports allege his passing was a suicide.
"My friend Ren Hang left us this morning in Berlin, I am sad and in shock," wrote Pierre Bessard of the Paris-based independent publishing house Editions Bessards Friday on his company's website.
Ren's self-titled photobook -- his first -- featuring major works from 2008 through 2015 was published by Taschen on January 20.
"There is no doubt that we have lost one of our era's best artists, a brave man," Vice China posted on their official account on China's Twitter-like Weibo platform.
"In his photographs and poems, he expressed admirable talent and honest heart; an artist can do no more."