In an exclusive interview Sunday, Brin told the newspaper there are "very powerful forces that have lined up against the open Internet on all sides and around the world."
"I am more worried than I have been in the past. It's scary," he said.
Brin said the threats to Internet openness come from three main areas: government control, anti-piracy initiatives from the entertainment industry and so-called walled gardens such as those created by Apple and Facebook.
Brin, 38, whose net worth is estimated at $18.7 billion, spearheaded Google's partial withdrawal from China in 2010 over censorship concerns.
"I thought there was no way to put the genie back in the bottle, but now it seems in certain areas the genie has been put back in the bottle," he said.
Brin surmised Google could not have been founded with an Internet dominated by Facebook, saying: "You have to play by their rules, which are really restrictive. The kind of environment that we developed Google in, the reason that we were able to develop a search engine, is the Web was so open. Once you get too many rules, that will stifle innovation."