Ujiteru was the third-born son (second to survive to adulthood) of Houjou Ujiyasu, younger brother of Houjou Ujimasa, and older brother of Houjou Ujikuni, Houjou Ujinori, Houjou Ujitada, Houjou Saburou (Uesugi Kagetora), and Houjou Ujimitsu. He was widely extolled for his courage and wisdom.
In 1559, he married Hisa, the daughter of Ooishi Sadahisa, master of Takiyama Castle in Musashi, and became Ooishi's adopted son and heir. (Later, Ooishi became a vassal of the Houjou clan, and Ujiteru regained the Houjou surname.)
In the following years, Ujiteru followed his father into several battles with neighboring clans, which greatly increased the Houjou sphere of influence. He also excelled at diplomacy, and maneuvered the alliance between the Houjou and Uesugi clans into place in 1569. He also secretly built up diplomatic relations with the Date Clan. Though he wanted the clan to form an alliance with the Oda Clan during Oda's period in power, the plan fell through because of opposition within the family and Oda's death.
In 1569, while the Takeda army was en route to a siege of Odawara Castle, a detachment of the Takeda army led by Oyamada Nobushige attacked Takiyama Castle, penetrating all the way to the outermost wall. Ujiteru crossed spears with Takeda Katsuyori during the battle. Ujiteru's forces managed to stave them off, but dissatisfied with Takiyama's defenses, Ujiteru abandoned it in favor of Hachiouji Castle.
In 1590, during Toyotomi Hideyoshi's Siege of Odawara, he entrusted his main castle, Hachiouji Castle to a loyal vassal and barricaded himself in Odawara. Due to that fact, Toyotomi saw him as one of the pro-resistance leaders, and demanded his death along with his brother Ujimasa's. Ujiteru committed seppuku with Ujimasa on August 10.
He wrote as his death poem:
「天地の 清き中より 生まれきて もとのすみかに 帰るべらなり」
which may be translated thus:
We are born into
the brightness betwixt heaven
and earth; yet there is
another dwelling to which
we must all someday return.