Born in New York City, he completed preparatory studies and became active with his brothers in a successful flour business which had been started by their father.
He served on the board of managers of the Society for the Reformation of Juvenile Delinquents in the city of New York from 1845 to 1866, and was Treasurer from 1857 to 1866.
Underhill was elected as a Whig to the Thirty-first Congress, holding office from March 4, 1849 to March 3, 1851. He was not a candidate for renomination in 1850. Underhill advocated an end to slavery, and also supported efforts to have former slaves settle in Liberia, with compensation paid to their former owners. Regarded as a moderate on the slavery issue, Underhill frequently conversed with Alexander H. Stephens, later Vice President of the Confederate States of America, as they sought ways to end slavery which would obtain enough public approval to avert the coming American Civil War.
After leaving office Underhill was President of the Mechanics & Traders' Insurance Company in New York City.
- Convention of Managers and Superintendents of Houses of Refuge and Schools of Reform in the United States of America, Annual Meeting Proceedings, 1858, page 10
- Bradford Kinney Peirce, A Half Century with Juvenile Delinquents, 1869, page 290
- New York State Assembly, Documents of the Assembly of the State of New York, Volume 2, 1859, page 118
- Underhill Society of America, Annual Report, 1904, page 28
- United States Congress. "Walter Underhill (id: U000009)". Biographical Directory of the United States Congress.
- Walter Underhill at Find a Grave
- Walter Underhill at Political Graveyard
|U.S. House of Representatives|
|Preceded by |
William B. Maclay
| Member of the U.S. House of Representatives |
from New York's 4th congressional district
March 4, 1849 – March 3, 1851
John Henry Hobart Haws