Yuriko Koike (小池 百合子, Koike Yuriko; born 15 July 1952) is a Japanese politician who has served as the Governor of Tokyo since 2016. Previously, she also served as a member of the House of Councillors from 1992 to 1993, a member of the House of Representatives from 1993 to 2016, Minister of the Environment under Junichiro Koizumi from 2003 to 2006, and Minister of Defense under Shinzo Abe between July and August 2007.

Born and raised in Ashiya, a wealthy, small, and popular city near Kobe in Hyōgo Prefecture, Koike graduated from Cairo University in Cairo, Egypt in 1976, and served as a member of the House of Representatives of Japan from 1993 until 2016, when she resigned to run for Governor of Tokyo. Previously, she also served as the Minister of the Environment under Junichiro Koizumi's cabinet from 2003 to 2006 and briefly as Minister of Defense under the first cabinet of Shinzo Abe in between July and August 2007.

Koike was elected Governor of Tokyo in 2016, becoming the metropolis' first female governor. Koike was re-elected in 2020 and 2024, winning 59.7% and 42.8% of the popular vote respectively.

Considered one of the most high-profile and well-known Japanese politicians, Koike has been frequently mentioned as holding Prime Ministerial ambitions. She ran in the 2008 Liberal Democratic Party leadership election, becoming the first woman to run for the leadership of a major Japanese political party, however she came in third place losing to Tarō Asō. In 2017, Koike left the LDP amid much media attention and launched two parties: the national party, Kibō no Tō (希望の党/Party of Hope) and the regional party Tomin First no Kai (都民ファーストの会/Tokyoites First Party). Kibō no Tō contested the 2017 general election with Koike as a leader, however the party underperformed expectations and mostly disappeared after merging with the Democratic Party for the People in 2018. The same year, Koike stepped down as leader of Tomin First and officially became independent. However, Koike continues to endorse and campaign for Tomin First candidates in Tokyo and the party still makes frequent use of her image and policies.

Koike has come under some scrutiny from Japanese liberals and Koreans in both Japan and Korea for her refusal to acknowledge the occurrence of 1923 Kantō Massacre, which mainly targeted ethnic Koreans, as well as her association with groups that are often labeled anti-Korean.

Koike was born on 15 July 1952 in Ashiya near Kobe in Hyōgo, Koike went to Kōnan Girls' Junior and Senior High School for her secondary education. Her father, Yūjirō Koike, was a foreign trade merchant who handled oil products. He was also involved in politics, supporting Shintarō Ishihara and the Tatenokai in the 1960s, and ran unsuccessfully for Japanese general election in 1969. Yūjirō emphasised to Yuriko that it was essential for Japan to strengthen relations with Arab countries to ensure a stable petroleum supply to prevent Japan being thrust into an oil war again in the future. After dropping out of Kwansei Gakuin University's School of Sociology in September 1971, she went on to study Arabic at the American University in Cairo and allegedly received a Bachelor of Arts in Sociology as the top student from Cairo University in October 1976. When she was 21, she married a fellow Japanese student but divorced soon after. She began to work as an interpreter of Arabic and later became a journalist, interviewing Muammar Gaddafi and Yasser Arafat in 1978, and becoming a news anchor in 1979. She received the Female Broadcaster of Japan award in 1990.

Koike has been alleged several times of falsifying her credentials, particularly regarding her graduation from Cairo University in Cairo, Egypt. In June 2020, Cairo University released a statement that "Cairo University certifies that Yuriko Koike... graduated from the Department of Sociology, Faculty of Arts, Cairo University in October 1976," denying the allegations.

Meanwhile, Egyptian allegations that she had committed job fraud first surfaced during 1992, they were more widely reported during the Tokyo's gubernatorial election in 2016, and first reported by Japanese news program Tokudane!. Koike sent her graduation certificate to the program in response to allegations. In January 2018, a woman who claimed to have been Koike's roommate at Cairo University wrote to the Japanese monthly magazine Bungei Shunjū after reading an article on Koike. In 2024, the magazine published an article on their website, including a video where Toshiro Kojima, a lawyer and former aide of Koike, said that he helped to falsify Koike's academic credentials including drafting a fake graduation document. Koike has denied the allegations.