During the first half of the 20th century, Castle Upton was sold by the Upton family. The Adam alterations to the roof were removed, and the Adam wing fell into disrepair. In 1963 the semi-ruined house was purchased by Sir Robin Kinahan, a prominent businessman and former Lord Mayor of Belfast, for £53,000. His wife, the artist Coralie de Burgh, guided the restoration of Castle Upton over the succeeding years. Improvements were continued by their son, Danny Kinahan and his wife Anna, who later opened the castle as a wedding venue. In 2016 the Kinahans placed Castle Upton on the market for £1.35m.