In 1794, he was elected by the General Assembly as a Federalist to be Governor of South Carolina. During his administration, Vanderhorst pressed the legislature for the revision of the criminal code because the sentences were so harsh that jurors would grant acquittal. In addition, he advocated for a prison system similar to that of the state of Pennsylvania instead of the state jails that "were of medieval barbarity."
He also proposed the need for a state penitentiary. Later the state penitentiary named Central Correction Institution that was open until 1994.
Later life
After leaving the governorship in 1796, he returned to his plantation on Kiawah Island where slaves he owned cultivated sea island cotton. Vanderhorst died on January 29, 1815, and he was buried at the St. Michael's churchyard in Charleston.