George Johnston was born on July 20, 1797, in Swinton or Simprin, Berwickshire, Scotland.

He was a Scottish physician, naturalist, and author. In his infancy, his family moved to Ilderton, Northumberland, England. Johnston was educated first at Kelso, then at Berwick grammar school, and finally at the University of Edinburgh (M.D., 1919). He was apprenticed to Dr. Abercrombie, and in 1817, he became a member of the Royal College of Surgeons of Edinburgh (R.C.S.E). In 1818, he began his practice in Berwick where he stayed for the rest of his life. In 1824, he became a Fellow of the R.C.S.E. He was thrice mayor of Berwick, and became LL.D. of Aberdeen. He retired from practice in 1853. Johnston was one of the founders of the Berwickshire Naturalists' Club and became its first president in 1831. In 1837, he became one of the editors of the Magazine of Zoology and Botany, later the Annals and Magazine of Natural History, the Edinburgh Philosophical Journal, Loudon's Magazine of Natural History, the Transactions of the Natural History Society of Newcastle, and he also contributed numerous papers to the Proceedings of the Berwickshire Naturalists' Club.

In 1819, he married Catharine Charles (1794-1871), an English botanical illustrator who illustrated many of his publications. He died on July 30, 1855, in Berwick, Sussex, England.