He was born in the city of Shōbara in Hiroshima Prefecture into a poor family. He studied at the department of economics at University of Tokyo and worked his way through school through various jobs, including singing at a cabaret.
Upon graduation in 1960, he entered Sumitomo Seika, and joined the National Police Agency in 1962. In 1972, he took charge of a number of high-profile cases, including the Red Army Asama-Sanso incident, the Narita Airport incident, and the Tel Aviv highjacking. Kamei is one of the few major politicians to oppose the death penalty, and wrote a book, Shikei Haishi ron, asserting his opposition.
In 1977, he left the agency and received 3.5 million yen in severance pay, which he used to run for the Diet in Hiroshima. He was elected in 1979 as a member of the Liberal Democratic Party (LDP).
In 1989, he formed the Freedom Reform Alliance, criticizing the LDP's system of factions and strongly supported Shintarō Ishihara. He became Minister of Exports in 1994 and Minister of Construction in 1996. In 1998, he left the Mitsuzuka faction and formed the "Nakayama-Kamei group" with Minister of Foreign Affairs Taro Nakayama.
In 1999, he headed up the LDP's Policy Research Council and founded the Kamei faction. In 2003, he unsuccessfully ran for the position of Prime Minister against the incumbent, Junichiro Koizumi.
He opposed Koizumi's postal privatization plan and left the LDP in 2005, forming the Kokumin Shinto (People's New Party) with four other Diet members. Despite facing the popular businessman Takafumi Horie in the 2005 election, he won reelection for the tenth time.
On September 16, 2009, Kamei became the banking and postal services minister in the newly formed Hatoyama cabinet. Throughout the week, he voiced his commitment to providing economic stability for small companies, whom he claimed "had lost vitality". He plans to provide a moratorium of up to three years on loan repayments and attempts to put a brake on what he perceives as excesses by financial and lending institutions.
After shifting parties twice, he is currently a political independent.
He is sometimes humorously referred to as Shizuka chan (where "chan" is a title usually reserved for young girls) after a female character in the manga Doraemon who shares his personal name.
The character "Takeo Tsuruta" in the manga Akumetsu is based on him.
In August 2003, Kamei acknowledged receiving political donations from the leader of a group of loan sharks affiliated to the Yamaguchi-gumi, the largest known yakuza syndicate in Japan. The donator was Susumu Kajiyama.
Kamei is a six-level blackbelt in Aikido and enjoys golf and oil painting.