Born on May 27, 1918, the second son of the timber merchant Nakasone Matsugoro in Takasaki-machi, Gunma District, Gunma (today Takasaki). After First Higher School he graduated from the Department of Political Science of the Faculty of Law, Tokyo Imperial University (1941), and entered the Ministry of Home Affairs. He served at the front as a navy paymaster officer, and at the end of the war was a navy paymaster lieutenant commander. In the 23rd general election of 1947 he was first elected from Gunma 3rd district as a Democratic Party endorsee (at 28); thereafter he was elected for 20 consecutive terms, with a parliamentary career of more than 56 years. In 1959 he first entered a cabinet as Director-General of the Science and Technology Agency in the Second Kishi Cabinet, and held Director-General of the Defense Agency, Minister of International Trade and Industry, Director-General of the Administrative Management Agency, and LDP Secretary-General. On November 27, 1982, succeeding Suzuki Zenko, he took office as the 71st prime minister. Through the 72nd and 73rd terms, three terms in all, he ran a long government of about five years. Raising the banner of 'a final reckoning of postwar politics,' he pushed the privatization of the three public corporations (Japan National Railways, Nippon Telegraph and Telephone Public Corporation, and the Japan Tobacco and Salt Public Corporation), the breaking of the 1 percent of GNP cap on defense spending, and the strengthening of the Japan-U.S. alliance. He showed his presence diplomatically too with the 'Ron-Yasu' honeymoon relationship with U.S. President Reagan, neighborhood diplomacy with visits to South Korea and China, and leadership of summits. He led the LDP to a sweeping victory in the simultaneous House of Representatives and House of Councillors election of 1986 and became a symbolic presence of postwar conservative politics. After resigning in November 1987 he also retained influence as a 'political heavyweight,' retiring as a Diet member in 2003 at 85. He died of senile decay in Tokyo on November 29, 2019, at 101.

A theorist with bold decisiveness combined. He had such political acuity that he was mocked as a 'weathervane,' and he moved between the Sato faction and the Fukuda faction within the party, while after becoming prime minister he set forth a clear national vision. He did not fear hawkish conservative remarks such as 'unsinkable aircraft carrier' and 'making the Japanese archipelago an unsinkable aircraft carrier,' but he was also a man of culture who loved kendo, haiku, and reading. Tall and well-built, he was also called the first prime minister to look good on television. He wrote many books and continued intellectual activity to the end of his life.

The privatizations under Nakasone administrative reform — the breakup and privatization of Japan National Railways (the launch of the JR companies in April 1987), the privatization of the Nippon Telegraph and Telephone Public Corporation (the launch of NTT), and the privatization of the Japan Tobacco and Salt Public Corporation (the launch of JT) — contributed greatly to improving the productivity of the Japanese economy as the largest structural reform of the postwar era. On the other hand, the breaking of the 1 percent of GNP cap on defense spending, the official visit to Yasukuni Shrine (1985, drawing reaction from neighboring countries and called off the next year), and education reform through the Ad Hoc Council on Education, with their direction of revising the postwar system, were carried on to the later Koizumi Junichiro and Abe Shinzo governments. The qualitative strengthening of the Japan-U.S. alliance through the 'Ron-Yasu' relationship laid the foundation of present-day Japan-U.S. relations. The Nakasone faction passed through the Watanabe faction and the Yamasaki faction and retains a certain influence within the LDP today. Near his birthplace in Takasaki, Gunma, the Nakasone Yasuhiro Memorial Hall has been built. His eldest son Nakasone Hirofumi is a former foreign minister.