Born in 1565 as the eldest son of Honda Masanobu, a chief retainer of Tokugawa Ieyasu, Masazumi served as a close aide to Ieyasu and later Shogun Hidetada, rising to the rank of roju (senior councilor). In 1619 he was transferred to Utsunomiya with a stipend of 155,000 koku, where he carried out a sweeping renovation of the castle — expanding its layout and adding new moats and earthworks — and reorganized the Nikko and Oshu highways, shaping the skeleton of the modern castle town. In 1622, however, he was accused of rigging a "suspended ceiling" trap in the castle to assassinate Hidetada during a planned stopover, an affair known as the Utsunomiya Castle Suspended Ceiling Incident. He was stripped of his domain and exiled to Yuri (later Yokote) in Dewa Province, where he died in 1637.

A capable administrator like his father, he wielded considerable influence at the heart of shogunate politics, though he is also said to have had an overbearing manner that drew resentment from rivals.

Remembered as the figure who shaped the layout of modern Utsunomiya, his name is inseparable from the castle's best-known legend, the Suspended Ceiling Incident.