WUZHEN, China — Little heard from but hugely influential, the professor-turned-Communist theoretician who has been a major adviser to three Chinese leaders finally stepped out of the shadows on Sunday.

Known as the brain behind President Xi Jinping, Wang Huning made his first major speech since joining the Politburo Standing Committee, the seven-member group that rules China, at a conference created to show off the country’s technological strengths to the world.

Well known for his icy remove and support of authoritarianism, Mr. Wang called for security and order on the internet as part of five proposals he made to guide the future of cyberspace. He also emphasized China’s technological prowess, and said more should be done by the government to guide the development of new industries like artificial intelligence and quantum computing.

Mr. Wang stepped onto the world stage before an audience that included Tim Cook, the chief executive of Apple, along with an all-star cast of Chinese tech entrepreneurs, such as Jack Ma of Alibaba.