17 Nov. 1767–1 Apr. 1859
De Rosset married Mary Fullerton, whose father was John Fullerton, a nephew of the Scottish philosopher David Hume, and whose mother was Elizabeth Toomer Fullerton. The couple had three daughters who died in infancy, and one son, Moses John De Rosset, born 11 Feb. 1796. The following year Mrs. De Rosset died, and on 1 Aug. 1799 Armand John married her sister, Catherine Fullerton. The children of the second marriage were Catherine G., Elizabeth Ann, Magdalen Mary, Mary Jane, Armand John, and two sons who died in infancy.
On 10 Oct. 1814 De Rosset was commissioned a surgeon in the Third Regiment of the North Carolina Militia, which was his only military service. For many years he served as a justice of the peace. He was not a frivolous man and organized the Nine-Penny Whist Club more to provide occasions on which the members could enjoy congenial discussions than to play cards. Members of his family had always served as wardens, vestrymen, lay readers, and treasurers of Saint James's Church—both while it was Anglican and later when it became a part of the Protestant Episcopal church—and he was active in all of its affairs. He assisted in the founding of the Bible Society in Wilmington in 1816, serving as vice-president and later as president. An affluent citizen, De Rosset was a director of the Bank of Cape Fear for thirty-seven years. He also invested $10,000 in The Rockfish Company and a similar sum in the road that became the Wilmington and Weldon Railroad.
A contemporary described De Rosset as "short in stature, being not over five feet four inches, with light blue eyes and ruddy complexion; not handsome, though a benign expression lent a pleasing and attractive appearance to his countenance." He was buried in Saint James's Churchyard, Wilmington.