Hōjō Tamemasa served as a bushō during the Sengoku period.

Tamemasa was born as the second son of Hōjō Ujitsuna.  The lineage from the era of Tamemasa is known as the Tamanawa-Hōjō family after the name of the castle where he served as its lord.

After the death of his uncle, Hōjō Ujitoki, he succeeded him at the age of twelve as the lord of Tamanawa Castle in the Kamakura District of Sagami Province.  On 7/23 of Kyōroku 5 (1532), he issued an official document with his seal.  This, however, appeared to be before his coming-of-age ceremony and when Daidōji Morimasa and Hōjō Tsunashige were supporting him.  Thereafter, he served as the lord and chamberlain of Kawagoe and Kozukue castles in Musashi Province and Misaki Castle in Sagami Province.

In 1532, Tamemasa engaged with Daidōji Morimasa and Kasahara Nobutame who were appointed as magistrates in charge of the reconstruction of the Tsurugaoka-Hachiman Shrine in Kamakura.  Tamemasa is surmised to have received one of the characters from the names of each of Morimasa and Nobutame.  Morimasa served in the honorary role to place the black-lacquered head gear known as an eboshi on Tamemasa at his coming-of-age ceremony and served as his guardian.  Thereafter, his name frequently appears in diaries associated with shrines and temples but, from around 1539, he no longer appears in records and is believed to have fallen ill.  He died in 1542 at the age of twenty-three.  He did not have children, so Hōjō Tsunashige (the natural son of Fukushima Masashige) inherited the headship of the clan in the capacity as an adopted son of Tamemasa.