He studied law at Litchfield Law School. He was admitted to the bar in 1821, and commenced practice in Palmyra. In 1833, he married Abbie Louise Hart (1814–1840), daughter of State Senator Truman Hart.
Theron R. Strong was District Attorney of Wayne County from 1835 to 1839.
He was a member from Wayne County of the New York State Assembly in 1842.
He was a justice of the New York Supreme Court (7th District) from 1852 to 1859, and ex officio a judge of the New York Court of Appeals in 1858. He removed to Rochester, New York, the seat of the district bench, and afterwards resumed the practice of law there.
He removed to New York City in 1867, and continued the practice of law.
He was buried at the Mount Hope Cemetery, Rochester.
- United States Congress. "Theron R. Strong (id: S001020)". Biographical Directory of the United States Congress.
- The New York Civil List compiled by Franklin Benjamin Hough (pages 227, 308, 352 and 384; Weed, Parsons and Co., 1858)
-  Court of Appeals judges
|U.S. House of Representatives|
|Preceded by |
| Member of the U.S. House of Representatives |
from New York's 25th congressional district