Born near New Athens, Ohio, Welch received a liberal schooling and graduated from Franklin College. He moved to Athens County in 1828 and settled in Rome Township. He engaged in the milling business. He studied law. He was admitted to the bar and commenced practice in Athens, Ohio, in 1833. He served as prosecuting attorney of Athens County 1841–1843. He served as member of the Ohio Senate 1845–1847.

Welch was elected as a Whig to the Thirty-second Congress (March 4, 1851 – March 3, 1853). He declined to be a candidate for renomination in 1852. He served as delegate to the Whig National Convention in 1852. He resumed the practice of law. Presidential elector for Republicans Fremont/Dayton in 1856^[1] He served as judge of the court of common pleas 1862–1865. He served as associate justice of the supreme court of Ohio 1865-1878 and was chief justice in 1877 and 1878. He died in Athens, Ohio, August 5, 1891. He was interred in West Union Street Cemetery.

Welch was married in 1829 to Martha Starr, who had two sons.^[2]

Welch, John (1887). An index-digest to the reports of cases decided in the courts of Ohio: embracing the Supreme, Circuit, Common pleas and Superior court decisions to May, 1886. Robert Clarke & co. OCLC 11767958.

• United States Congress. "John Welch (id: W000263)". Biographical Directory of the United States Congress.
• Smith, Joseph P, ed. (1898). History of the Republican Party in Ohio. Vol. I. Chicago: the Lewis Publishing Company.
• Smith, Joseph P, ed. (1898). History of the Republican Party in Ohio. Vol. II. Chicago: the Lewis Publishing Company.

  This article incorporates public domain material from the Biographical Directory of the United States Congress

• "Welch, John" . Appletons' Cyclopædia of American Biography. 1900.