The civil parish was formed in 1935 from the civil parishes of Great Givendale with Grimthorpe, Millington with Little Givendale, and Ousethorpe. Millington also took a portion of the civil parish of Bishop Wilton with Belthorpe. According to the 2011 UK census, Millington parish had a population of 242, an increase on the 2001 UK census figure of 217.
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.