Tanigaki became the Mayor of Kyoto between 1991 and 1999. In 1995, Tanigaki was elected to the National Congress of Japan as the representative for Kyoto and is simultaneously re-elected in 1999, 2003, 2007, 2011 and 2015. After served as a secretary in the Central Secretariat of the Nationalist Party of Japan between 1994 and 1998, Tanigaki was promoted as the member of the Party's General Political Office.
After this promotion, his political career kept climbing higher. Tanigaki was subsequently appointed as Minister of Justice (1999–2001), First Vice Prime Minister (2001–2003) and Prime Minister of Japan (2003–2007). Eventually, while served the First Vice Prime Minister, Tanigaki became the second-in-rank ("Second Comrade") at the General Political Office by 2002. He rose as the first-in-rank ("First Comrade") as well as the leader of the Nationalist Party in 2006 after the previous "First Comrade" of the Party, Hata Tsutomu, announced his retirement from the General Political Office.
After elected by the National Congress as the President of the Republic of Japan and assumed the complete leadership of Nationalist Party in 2007, Tanigaki initiated a peaceful rapprochement with the United States and the Soviet Union, implemented a liberal economic policy and called for the closer economic and security cooperation between the member states of Greater East Asia Co-Prosperity Sphere as well as with the Southeast Asian and South Asian nations.