He married in 1814 Catherine, eldest daughter of Peter Finch Martineau, by whom he had one son, who died in infancy, and in 1844 Maria Elizabeth Hutchins (at St Leonard's) , eldest daughter of William Hutchins, by whom he had six sons (of whom the eldest, Edward, a barrister, assisted in the preparation of the ‘Biographia Juridica’) and three daughters. One of his grandsons was the composer, critic, and publisher of music Hubert J. Foss.
Edward Foss (1787–1870), legal writer and biographer, eldest son of Edward Smith Foss (d. 1830), solicitor, of 36 Essex Street, Strand, London, and Anne, his wife, daughter of Dr William Rose of Chiswick, was born in Gough Square, Fleet Street, on 16 October 1787. He was educated under Dr Charles Burney, his mother's brother-in-law, at Greenwich, and remained there until he was articled in 1804 to his father, whose partner he became in 1811. In 1822 he became a member of the Inner Temple, but never proceeded further towards a call to the bar, maintaining instead a highly successful solicitor's practice.
Foss held a number of other offices during his life. In 1827–8 he served as under-sheriff of London. He was connected with the Law Life Assurance Society from its foundation in 1823, first as auditor and afterwards as director, and was active in founding the Incorporated Law Society, of which he was president in 1842 and 1843. In 1844 he moved from Streatham to Canterbury, where he proved himself a useful chairman of the magistrates' bench; he later became deputy lieutenant for Kent.
Image Edward Foss (Thomas Griffiths Wainewright, circa 1816)