He graduated from Sophia University before working at the Asahi Shimbun newspaper, and was elected to the National Diet in 1971 before leaving to serve as governor of his home prefecture from 1983 to 1991.

He was elected to the House of Councillors of Japan as an LDP representative of Kumamoto Prefecture in 1971, with his campaign funded by party boss Kakuei Tanaka.

[5] In May 1992, an ongoing campaign contribution scandal inspired him to form the reformist Japan New Party (JNP), which won four seats (one of which Hosokawa assumed) in the 1992 House of Councillors election.

[6] The Hosokawa government pushed for changes to Japanese election laws intended to fight political corruption, including elimination of corporate political donations to individual candidates and a redrawing of the electoral system, both intended to prevent the LDP from continuing to employ its past electoral practices.

After an extended legislative fight, the LDP was able to force several concessions to maintain their advantage, retaining corporate political donations with a cap, while pushing back on some more radical changes to the electoral map and ensuring that most candidates would keep essentially the same seats in the next election.

Amendments made to regulations under the Industrial Safety and Health Law of 1972 on 30 March 1994 included accidents involving the collapsing of cranes and breaking of wires that needed to be reported to the authorities.

[12] Hosokawa also enacted cuts in income and resident taxes, intended to help Japan out of the recession that had followed the Japanese asset price bubble of the late 1980s and early 1990s.

The move was controversial within the cabinet, as Ichiro Ozawa favored a 10% rate while the Japan Socialist Party would not agree to an increase.

[13][14][15] Hosokawa was forced to resign in April 1994 after it came to light that he had accepted a 100-million-yen loan from a trucking company previously accused of bribery and links to organized crime.

Amid allegations of bribery, Hosokawa argued that the money was a loan and produced a receipt to show that he had paid it back; LDP members passed around a copy remarking that it looked like a fake.

[citation needed] Although Hosokawa still had high public approval at the time, opinion was growing that he could not meet the expectations set at the start of his term.

[16] Hosokawa's resignation was abrupt and led to a number of frenzied meetings aimed at saving the coalition, which was torn between the rival camps of Ichiro Ozawa and Masayoshi Takemura.

Although this idea was not popular within the LDP and never came to fruition, Hosokawa and Koizumi maintained a close working relationship in subsequent years.

He also criticized Abe's foreign policy in the run-up to the 2020 Summer Olympics in Tokyo, questioning "whether pugnacious diplomacy will help the festival of peace to be held smoothly.

[28] Masuzoe was declared the winner in exit polls shortly after voting ended on February 9, but Hosokawa vowed to continue anti-nuclear advocacy.

[22] His wife, Kayoko Hosokawa, to whom he has been married since 23 October 1971, served as honorary chair of the Special Olympics Nippon Foundation and headed NPOs devoted to providing vaccines to children in developing nations and helping the intellectually disabled.