Borlase was born on 2 February 1695/6 at Pendeen, of an ancient family originating at St Wenn. He was educated at Exeter College, Oxford from 1713, and in 1719 he was ordained. In 1722 he was presented to the rectory of Ludgvan, and in 1732 he obtained in addition the vicarage of St Just, his native parish. The garden of the Rectory (now known as Hogus House) was established by Borlase; during the reign of Queen Victoria the garden was further developed by a successor, Arthur Boscawen, and was known for its fine collection of trees and shrubs.