Hoare was born at Eye, Suffolk, 1707. He was the son of a prosperous farmer and brother to the sculptor Prince Hoare (d.1769). Hoare was a pupil of Guiseppe Grisoni (1699–1769) with whom he went to Italy in 1728. He stayed for nine years, studying under Imperiali and supporting himself comfortably by copying famous masterpieces.

Hoare then settled in Bath 1739 and was its most fashionable portraitist in oil and crayons until the arrival of Gainsborough in 1759, although he remained in demand until giving up painting in about 1779.

Hoare died in Bath on the 9th December 1792, in prosperous circumstances. His son Prince Hoare (1755–1835), also a painter, studied under him and under Mengs in Rome, but gave up painting for writing after 1785.