After attending Dummer Charity School (now The Governor's Academy), Sewall graduated from Harvard College (A.B. 1776, A.M. 1779, honorary LL.D. 1808) and set up practice as a lawyer in Marblehead. He served as a member of the state legislature in 1783, and from 1788-96.
He represented Massachusetts in the U.S. House of Representatives from 1796 to 1800, and from 1800 to 1814 served as a judge of the Massachusetts Supreme Judicial Court, becoming Chief Justice in 1814. He died at Wiscasset in Massachusetts' District of Maine while holding a court there. He was elected a Fellow of the American Academy of Arts and Sciences in 1801.
American novelist Louisa May Alcott was Sewall's great niece. His younger sister, Dorothy, was Alcott's great-grandmother. In 1781, he married Abigail Devereux; they had a family of at least six sons and two daughters. Sewall's great-grandfather Samuel Sewall was a judge at the Salem witch trials in colonial Massachusetts, and subsequently Chief Justice of Massachusetts.
Sewall was elected a member of the American Antiquarian Society on June 1, 1814. Sewall died 7 days later on June 8, apparently before he could formally respond, so his disposition regarding membership is unknown.
- Graves, Eben W. (2007). The Descendants of Henry Sewall (1576-1656) of Manchester and Coventry, England, and Newbury and Rowley, Massachusetts (1st ed.). Boston, Massachusetts: Newbury Street Press. p. 229. ISBN 978-0-88082-198-8.
- "Book of Members, 1780–2010: Chapter S" (PDF). American Academy of Arts and Sciences. Retrieved August 7, 2014.
- Powell, Kimberly. "Ancestry of Louisa May Alcott". About.com. Retrieved July 29, 2014.
- American Antiquarian Society Members Directory
- Roberts, Robert B. (1988). Encyclopedia of Historic Forts: The Military, Pioneer, and Trading Posts of the United States. New York: Macmillan. p. 410. ISBN 0-02-926880-X.
|U.S. House of Representatives|
| Member of the U.S. House of Representatives
from Massachusetts's 10th congressional district
December 7, 1796 – January 10, 1800
| Associate Justice of the Massachusetts Supreme Judicial Court
| Chief Justice of the Massachusetts Supreme Judicial Court