Historically, Bellasize was in the ecclesiastical parish of Howden in the wapentake of Howdenshire. From 1894 until 1974, Bellasize was located in Howden Rural District. In 1935 Bellasize was abolished and the area was transferred into the civil parish of Blacktoft.
In 1974 most of what had been the East Riding of Yorkshire was joined with the northern part of Lincolnshire to became a new English county named Humberside. The urban and rural districts of the former counties were abolished and Humberside was divided into non-metropolitan districts. The new organization did not meet with the pleasure of the local citizenry and Humberside was wound up in 1996. The area north of the River Humber was separated into two "unitary authorities"—Kingston-upon-Hull covering the former City of Hull and its closest environs, and the less urban section which, once again, named itself the East Riding of Yorkshire.