Rüütel was born in 1928 on the island of Saaremaa in the independent Republic of Estonia. A trained agronomist, he was one of the leaders in Estonia's agricultural sector. In 1983, he became the chairman of the Presidium of the Supreme Council of the Estonian SSR, which was part of the Soviet Union.
As one of the leaders of the republic and the Communist Party of Estonia, he supported the movement for sovereignty and later for the restoration of Estonia's independence from the USSR. As early as 1988, the Supreme Council of the Estonian SSR, under Rüütel's leadership, adopted a declaration of sovereignty, and after the 1990 elections, the newly elected Supreme Council, where independence supporters held the majority, enacted a law restoring the Constitution of the independent Republic of Estonia from 1938. The formal announcement of the restoration of independence was made in August 1991. Rüütel presided over the Supreme Council until 1992, when it was transformed into the parliament - Riigikogu.
In 1992, Rüütel contested the re-established presidency but lost the election to Lennart Meri. He also lost the 1996 elections but was elected president in 2001, serving one term until 2006. He was the leader of the conservative People's Union party. As one of Estonia's leading politicians in the 1990s and 2000s, the official obituary states that he "instilled confidence in many people's belief that joining the European Union and NATO was in Estonia's national interests." Estonia joined these organizations during Rüütel's presidency.