Herman Welker was born in Cambridge, Idaho, December 11, 1906, the youngest of the seven children of John T. and Zelda Shephard Welker. Both of his parents were from North Carolina, but came west and settled in Cambridge where John Welker was a potato grower. Herman attended grade school in Cambridge and high school in Weiser. After graduating from Weiser High School in 1924, he attended the University of Idaho, spending two years in a general studies program before attending law school for three years. In 1929 he received his LL.B. degree.

In 1928, while still a student at the university, he was appointed Prosecuting Attorney of Washington County and was twice re-elected to that position.

In September of 1930 Welker married Gladys Taylor Pence; they had one daughter, Nancy.

Between 1936 and 1943 he practiced law in Los Angeles, California, and, after spending a year in the Air Corps, he returned to Idaho, where, from 1944 to 1950 he had his legal practice in Payette.

In 1948 he was elected to the Idaho State Senate on the Republican ticket, and served in one regular and one special session. In 1950 D. Worth Clark defeated the incumbent, Glen Taylor, for the Democratic U.S. Senate nomination; Clark, in turn, was overwhelmingly defeated by Welker in the general election, 124,237 to 77,180. While in the Senate he served on the Armed Services Committee, the Internal Securities subcommittee of the Committee on the Judiciary, the Committee on Post Office and Civil Service, the Committee on Agriculture and Forestry, and the Committee on Rules and Administration. A strong supporter of the right wing of the Republican party, Welker was also a close associate of Senator Joseph McCarthy. In 1954 he was McCarthy's chief defender in the debate which led to McCarthy's censure by the Senate. Welker won the Republican nomination for re-election in 1956, but was defeated in the general election by Frank Church by a vote of 149,096 to 102,781. Following his defeat he practiced law in Boise.

Welker was a member of the Masonic Lodge, El Korah Shrine, Elks, Knights of Pythias, American Legion, IOOF, Idaho Bar Association, California Bar Association, Sigma Chi, Phi Alpha Delta (Honorary Law Fraternity), and the Idaho Cattlemen's Association.

On October 16, 1957, the 50 year old former Senator was admitted to the National Institutes of Health, Washington, D.C., where he underwent brain surgery on October 17 and again on the 28th. He died at the clinic on Wednesday, October 30, 1957. On November 1, approximately 150 people attended the military service held in the Fort Meyer, Virginia, chapel, where Welker was eulogized for his relentless fight against communism. He was buried the same day in Arlington National Cemetery.