Zhou, who was probably China's oldest dissenter, died Saturday at his house in the country's capital, a day after having celebrated his 111th birthday, state media said.
"He lived through many eras and helped enlighten ordinary people," the Communist Party mouthpiece the People's Daily said.
Zhou is commonly known as the "father of Pinyin", a system for transliterating Chinese characters into the Roman alphabet introduced in the 1950s and now used by hundreds of millions of language learners in China, as well as abroad.
He avoided China's civil war between the Communists and Nationalists by going to work for a Chinese bank on Wall Street, twice meeting Albert Einstein while visiting friends at Princeton.
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But following the Communist victory in 1949, Zhou returned home to teach economics and became a close associate of the party's number two, Zhou Enlai.
He was attracted to Mao Zedong's Communists because "at that time they promoted themselves as democrats", he wrote in a 2012 autobiography.
An amateur linguist who had taught himself some Esperanto, Zhou was assigned in 1955 to co-chair a committee tasked with increasing literacy by reforming the Chinese language.
The proposal, named Pinyin -- "putting together sounds" -- is used in schools across China and has been instrumental in boosting the country's literacy rate from around 20 percent in the 1950s to more than 90 percent today.
In recent decades, Pinyin has become key to the easy creation of Chinese characters on computers.
But Zhou's contributions did not save him from the chaos of Mao's decade-long Cultural Revolution from 1966, during which intellectuals were persecuted.
He has described the two decades from 1960 to 1980 as "wasted", adding: "In all honesty I haven't got anything good to say about Mao Zedong."
He had a higher opinion of Mao's successor Deng Xiaoping, who launched market-style reforms which helped transform China into the world's second-largest economy.