Zhou Youguang, a onetime Wall Street banker from China who developed Pinyin, a Romanized writing system that has helped more than 1 billion Chinese and countless foreigners learn Mandarin, died Jan. 14 in Beijing, one day after celebrating his 111th birthday.

State-run media outlets in China confirmed his death but did not provide additional details. In addition to his contributions to language, Mr. Zhou also survived three years of exile and forced labor to become one of his country’s most outspoken dissidents.

Mr. Zhou’s writing system, formally known as Hanyu Pinyin — or “putting sounds together,” as its name is sometimes translated — had a transformative effect on Chinese society.

Before its creation in the mid-1950s, about 85 percent of China was illiterate. Today, China claims near-universal­ literacy, in part through Mr. Zhou’s linguistic innovation.

Its impact is felt everywhere — from streets in Beijing, where signs provide Pinyin spellings alongside names written in China’s ancient script, to the name of the capital city. Following Mr. Zhou’s system, Peking became Beijing, the city of Nanking became Nanjing, and Mao Tse-tung — the Communist Party leader who initiated a wave of linguistic changes that included the adoption of Pinyin — became Mao Zedong.

Pinyin gave rise to a Chinese version of Braille, the language for the blind, and enabled China to transition almost seamlessly to the digital age: On most laptops and cellphones, people people type Pinyin letters that are automatically converted to Chinese ­characters.

In an interview, Victor H. Mair, a professor of Chinese language and literature at the University of Pennsylvania and a friend of Mr. Zhou’s since the early 1980s, described Pinyin as a simple, even elegant “transcription system” for Mandarin Chinese, the country’s official language.

For more than 2,000 years, Mair said, learning Chinese — a family of languages that includes Cantonese and Mandarin, which share the same script but have wildly different pronunciations — has amounted to a gargantuan task of rote memorization. According to Mair, there are more than 80,000 characters in the Chinese script, and most of them “give only a hint of their sound and a hint of their meaning.”

To achieve even the most basic level of literacy requires memorizing at least 1,500 characters. To read novels, newspapers and the like requires no fewer than 3,000 characters.

Mr. Zhou’s alphabet was not the first of its kind — a British system known as Wade-Giles was a popular Chinese transliteration tool in the early 20th century — but it was the first to acquire the imprimatur of the Chinese government.

Taught in elementary schools throughout China, Pinyin acts as a kind of linguistic crutch, enabling students to learn the sounds of words through its 25-letter, four-diacritical-mark system before advancing to the memorization and study of the characters themselves.

“Without an alphabet you had to learn mouth to mouth, ear to ear,” Mr. Zhou told Britain’s Guardian newspaper in 2008. “It’s a bridge to speech between Chinese people.”

Although Mr. Zhou — his full name is pronounced Joe Yo-Gwong — helped China better communicate within its borders and with the world at large, he did not escape the Cultural Revolution, a decade-long political campaign in which millions of Chinese were purged and ­persecuted.

Born Jan. 13, 1906, into a well-to-do family in the eastern city of Changzhou, Mr. Zhou was raised in a China where the Qing Dynasty still ruled, women bound their feet and men wore their hair in long braids.

He studied economics and linguistics at St. John’s University in Shanghai, one of the country’s oldest Western-style colleges, before transferring to Guanghua University and graduating in 1927 to begin a career as a banker.

Early in life he also changed his given name: Born Zhou Yaoping, he took on the name Yaoguang, which means “to illuminate,” because “he wanted it to be an indication of his bringing light” into the world, Mair said.

Mr. Zhou married Zhang Yunhe in 1933 and studied for several years in Japan, returning to China after the escalation of the Second Sino-Japanese War. They settled in Chongqing, the country’s wartime capital. While there, their 5-year-old daughter died of appendicitis. Mr. Zhou struck up a friendship with Zhou Enlai, a Communist Party official who hosted intellectual gatherings in the city and later became the country’s premier.

Mr. Zhou and his family moved to New York in 1946, where he represented the Sin Hua Trust and Savings Bank on Wall Street and twice met Albert Einstein on visits to Princeton University. (“I didn’t understand relativity at all,” Mr. Zhou later told China Daily, “so we just chatted about everyday things.”)

Safely away from the violence of the Chinese Civil War, he returned to Shanghai to teach economics in 1949, just as the Communists seized power in Beijing. He returned to see his mother and because “I thought the country had been liberated, and had a new hope,” he later wrote in an auto­biography.

The hope did not last long. In the mid-1950s, Mao embarked on a crusade against “rightists,” presumed political enemies that included proponents of capitalism and economists such as Mr. Zhou. One of his students committed suicide; a good friend, he later told the Guardian, was imprisoned and also committed suicide.

Mr. Zhou was spared mainly because of his friendship with Zhou Enlai, by then China’s premier and who recalled the economist’s fascination with linguistics and Esperanto, the global lingua franca. In 1955, he summoned Mr. Zhou to Beijing and tasked him with developing a new alphabet for China.

Mr. Zhou resisted before deciding on a crucial career change. “I said I was an amateur, a layman, I couldn’t do the job,” he told NPR in 2011. “But they said it’s a new job, everybody is an amateur.”

Working with a team of around 20 people, Mr. Zhou considered more than 2,000 writing systems, according to a 2004 account in the New Yorker. He eventually settled on a transcription system that used the Roman alphabet — a crucial point for Mr. Zhou, who later explained that he chose the Roman alphabet over Cyrillic (the alphabet used by China’s ally, the Soviet Union) because of its predominance in the world.

“Perhaps it was due to my time overseas, but I always envisaged Pinyin being useful to foreigners, too,” he told China Daily in 2009. “I still see it as a bridge between China and the rest of the world, a bridge between cultures.”

Pinyin was adopted by China’s First National People’s Congress on Feb. 11, 1958. The writing system was later approved by foreign bodies including the United Nations, which formally acknowledged Pinyin in 1986.

Mr. Zhou escaped the political purges of the 1950s — he told the Guardian that were it not for his linguistics background, he believed he “could have been imprisoned for 20 years” as an economist. But his business experience caught up to him during the Cultural Revolution of the 1960s and ’70s.

Deemed a reactionary, he was exiled to the Ningxia region of northwestern China in 1969, where he languished in rice fields before returning home to Beijing and his linguistics work in 1972.

Mr. Zhou oversaw a translation of the Encyclopaedia Britannica into Chinese in the mid-1980s and continued publishing books and scholarly articles on linguistics, Confucianism and Chinese history until shortly before his death.

Working out of a largely undecorated third-floor apartment in Beijing, surrounded by books that included his more than 40 published works — some of them banned in his home country — Mr. Zhou also became one of China’s most vocal critics.

Of Mao, the New York Times quoted him as saying in 2012: “I deny he did any good.” Of the 1989 Tiananmen Square massacre he said, “I am sure one day justice will be done.”

Although he lived without close family members in his final years — his wife died in 2002 and their son, astrophysicist Zhou Xiaoping, died in 2015 — Mr. Zhou was known for a seemingly unflagging optimism and defiant spirit. He seemed unconcerned about the prospect of government reprisal for his political commentary, joking to the BBC in 2012: “What are they going to do, come and take me away?”