Utsunomiya Hirotsuna served as a daimyō during the Sengoku and Azuchi-Momoyama periods.  He was the twenty-first head of the Shimotsuke-Utsunomiya clan.

In 1545, Hirotsuna was born as the son of Utsunomiya Hisatsuna.  During the Sengoku period, the Ise faith was popular in Shimotsuke Province and, perhaps owing to that influence, his childhood name was Ise Jumaru.

In 1549, his father, Hisatsuna, was killed in the Battle of Kitsuregawa-Sōtomezaka, an elder named Mibu Tsunafusa revealed his personal ambitions by seizing Utsunomiya Castle.  Tsunafusa welcomed Haga Takateru, the son of Haga Takatsune, to serve as the ostensible head of the Utsunomiya clan under the control of Tsunafusa.  While subordinating the Shionoya and other senior retainers of the Utsunomiya, Tsunafusa opposed Hirotsuna and, aiming to unify the province, he invaded other areas of Shimotsuke.  These developments posed a threat to the continued existence of the Utsunomiya whose years of peak prosperity were over.  Notably, from 1521 to 1528, the conflict between Utsunomiya Tadatsuna (the eighteenth head of the Shimotsuke-Utsunomiya) and his band of retainers led by Haga Takatsune, an event known as the Daiei Discord, marked the beginning of the decline of the Utsunomiya clan.

When Tsunafusa seized control, Hirotsuna was a young child.  Under the protection of Haga Takasada, he safely escaped from Utsunomiya Castle and was raised at Mooka Castle with the support of Takasada.  In 1551, Takasada carried out a plot by murdering his father’s archenemy, Nasu Takasuke.  In 1555, Takasada lured a resistant Haga Takateru to Mooka Castle and assassinated him.  That same year, Tsunafusa suddenly died and was succeeded by his lineal heir, Mibu Tsunatake, as the next lord of Utsunomiya Castle.  During this period, the Mibu continued an offensive, toppling Uba-ga-i and Yatsugi castles.  Thereafter, through the efforts of Takasada, the Utsunomiya gradually regained power, bolstered by an alliance with Hōjō Ujiyasu.  In 1557, upon orders of Ujiyasu, Satake Yoshiaki led a contingent of 5,000 soldiers on a deployment to Shimotsuke in support of Hirotsuna and Takasada, establishing a base at Tobiyama Castle.  Takasada enabled Hirotsuna to return to Utsunomiya Castle and avoid the elimination of the Utsunomiya clan.

In 1558, Echigo-Uesugi forces invaded Shimotsuke but owing to the valiant fighting of a retainer named Takō Nagatomo, Hirotsuna successfully repelled them.  Thereafter, through the diplomatic skills of Takasada, Hirotsuna received as his wife the daughter Yoshiaki, Nanryoin, reinforcing the strength of their political alliance.  Hirotsuna entered into an alliance with Uesugi Kenshin, coming into conflict with the Gohōjō aiming for a hegemony in the Kantō as well as the daimyō aligned with them.  In 1564, in the immediate aftermath of the Battle of Sannōdō, Uesugi Kenshin and Satake Yoshishige defeated Oda Ujiharu, the lord of Oda Castle, in the Siege of Oda Castle in Hitachi Province.

Hirotsuna was, by nature, frail of health.  During the Genki era (1570 to 1573), his health deteriorated to the extent he could not affix his seal to documents.  Minagawa Toshimune, a senior retainer of the Utsunomiya clan, took advantage of the circumstances by devising a plan to take over Utsunomiya Castle.  The threat to southern Shimotsuke posed by the alliance between Takeda Shingen and Hōjō Ujimasa known as the kōsō-dōmei, or the Alliance between Kai and Sagami Provinces, was a primary catalyst for Toshimune to seize control of Utsunomiya Castle.

On the evening of 1/14 of Genki 3 (1572), Okamoto Sōkei, the head of senior retainers of the Utsunomiya clan in charge of diplomatic relations with Uesugi Kenshin, was assassinated by Toshimune.  The next day, the Minagawa clan occupied Utsunomiya castle.  For approximately one year thereafter, Toshimune held the leadership of the Utsunomiya clan and gradually turned in favor of the Gohōjo clan.  Consequently, the Utsunomiya clan submitted to the Gohōjō.

In 1573, Hirotsuna joined with Satake Yoshishige from an allied province to subdue the Minagawa clan.

On 8/7 of Tenshō 4 (1576), Hirotsuna died of illness at the age of thirty-two.  He was bed-ridden throughout his final years.