Born near Bluffton, Ohio, and Pandora, Ohio, Welty's parents emigrated from Switzerland to Ohio in the mid-1800s. He attended the common schools and the Tri-State Normal College of Indiana. He graduated from the Ohio Northern University at Ada in 1894 and from the University of Michigan at Ann Arbor in 1896. He studied law, and was admitted to the bar in 1896 and commenced practice in Lima, Ohio. He served as city solicitor of Bluffton 1897–1909. He also served as a private during the Spanish–American War.

He became prosecuting attorney of Allen County 1905–1910, and was a lieutenant colonel in the Ohio National Guard 1908–1913. He served as special counsel to the Ohio Attorney General 1911–1913, and was a special assistant in the United States Department of Justice 1913–1915.

Welty was elected as a Democrat to the Sixty-fifth and Sixty-sixth Congresses (March 4, 1917 – March 3, 1921). He was an unsuccessful candidate for reelection in 1920 to the Sixty-seventh Congress.

After his Congressional career, he was employed with Inland Waterways Association 1921–1924. He resumed the practice of law until 1951, when he retired. He died in Dayton, Ohio, October 23, 1962. He was interred in Woodlawn Cemetery, Shawnee Township, Ohio.

• United States Congress. "Benjamin F. Welty (id: W000291)". Biographical Directory of the United States Congress. Retrieved on 2009-03-04

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