Hosokawa Tadakata served as a bushō during the Sengoku period.  He was the fourth head of the Hosokawa-Tenkyū, a cadet family of the Hosokawa clan.  Hosokawa Takakuni, who succeeded to the headship of the Hosokawa-Keichō, the main branch of the Hosokawa, was an elder cousin of Tadakata.

Tadakata was born as the son of Hosokawa Harutomo, the head of a cadet family of the Hosokawa-Yashū family.  Tadakata’s older brother, Hosokawa Kunitoyo, was appointed as the military governor of Bitchū Province and his younger brother, Hosokawa Takamoto, inherited the family of the military governor of the lower districts of Izumi Province.

Tadakata was adopted by Hosokawa Masakata, the third head of the Tenkyū family but, during the Eishō Disturbance, he followed Takakuni.  Based on genealogical records, he wed a granddaughter of Hosokawa Masakuni who, in turn, was Masakata’s father.

In 1511, at the Battle of Funaokayama, Masakata was killed in battle against Takakuni.  Thereafter, Takakuni allowed Tadakata to inherit the headship of the Tenkyū family in service to Takakuni.  Tadakata, via Takakuni, requested and received permission to use one of the characters from the name of Ashikaga Yoshitada, the tenth shōgun of the Muromachi bakufu, and adopted the name of Tadakata.  The character of “kata” was customarily used by members of the Tenkyū family.  He also used the separate name of Tadamoto, with “moto’ being a commonly used character in the name of members of the Hosokawa clan.  Meanwhile, Masakata’s son, Hosokawa Sumikata, and son, Hosokawa Harukata, maintained their opposition to Takakuni, causing the Tenkyū family to rupture.

In 1526, Tadakata slandered a senior retainer of Takakuni named Kōzai Motomori whereupon Takakuni had Motomori executed.  As a result, siblings of Motomori, namely, Hatano Motokiyo and Yanagimoto Kataharu, raised arms against Takakuni and Tadakata from Tanba Province.  In addition, Hosokawa Harumoto and Miyoshi Motonaga rebelled from Awa Province.  Tadakata, upon orders of Takakuni, attacked Motokiyo and his collaborators but was defeated.  In 1527, he fought against the allied forces of Miyoshi Masanaga and Yanagimoto Kataharu but lost again in the Battle of Katsurakawara.  He then joined Takakuni and Ashikaga Yoshiharu (the twelfth shōgun) to flee to Ōmi Province.

In 1528, Tadakata joined Takakuni in a bid to reclaim Kyōto but was defeated by Harumoto so Tadakata cut ties with Takakuni who was on the wane and defected to the side of Harumoto.  In 1531, Tadakata, together with Miyoshi Motonaga, defeated and killed Takakuni at the Collapse at Daimotsu.  Soon thereafter, he had a falling out with Harumoto.  On 7/24, Kizawa Nagamasa, acting upon orders of Harumoto, murdered Tadakata in Settsu.  According to the diary of Konoe Hisamichi, Tadakata was hiding in Tonda and took his life by drowning so the Kizawa forces were searching for him.  In fact, it appears that after he departed Tonda, he attempted to cross the Yodo River but failed and, with nowhere to turn, took his own life via drowning.

His eldest son, Hosokawa Ujitsuna, was adopted by Takakuni so his second son, Hosokawa Fujikata, inherited the Hosokawa-Tenkyū family.  Prior to Fujikata, however, Ujitsuna is deemed to have served as the head of the Tenkyū family.  Ujitsuna subsequently opposed Harumoto who was an archenemy of Tadakata as well as Takakuni.