The land that would become Blaise Castle was originally owned by the Kingsweston estate, and was part of a deer park that had been in use since the Middle Ages. In the 17th century, the land was sold to a local merchant named Thomas Farr, who built a house on the site. In the late 18th century, the house and estate were purchased by John Harford, a wealthy banker and philanthropist. He commissioned architect William Paty to redesign and expand the house, and the resulting Blaise Castle House is considered one of the finest examples of Georgian architecture in the region.

Harford also commissioned landscape designer Humphry Repton to create the parkland and gardens surrounding the house. Repton's design included a serpentine lake, a walled kitchen garden, and a range of ornamental buildings, including a folly known as Blaise Castle, which gave the estate its name and is now likely its best known feature.

The estate remained in the Harford family until the early 20th century, when it was sold to Bristol City Council. The house and grounds were opened to the public as a park, and over the years, new features were added, including a museum and art gallery, a playground, and a cafe.

Today, Blaise Castle is a popular destination for visitors to Bristol, offering a glimpse into the region's rich history and heritage, as well as a range of outdoor activities and attractions.