The annual Freedom House study of 65 countries found global internet freedom declined for the eighth consecutive year in 2018, amid a rise in what the group called "digital authoritarianism."
The Freedom on the Net 2018 report found online propaganda and disinformation have increasingly "poisoned" the digital space, while the unbridled collection of personal data is infringing on privacy.
"Democracies are struggling in the digital age, while China is exporting its model of censorship and surveillance to control information both inside and outside its borders," said Michael Abramowitz, president of Freedom House.
"This pattern poses a threat to the open internet and endangers prospects for greater democracy worldwide."
Chinese officials have held sessions on controlling information with 36 of the 65 countries assessed, and provided telecom and surveillance equipment to a number of foreign governments, Freedom House said.