Born Helen Margaret Palmer, Helen was the only Republican woman to ever represent Idaho in the United States Congress. Since her retirement in 2001, no woman has been elected to Congress from Idaho.

Helen's family moved to Southern Oregon when she was 12 to run a dairy farm near Grants Pass. She attended Whitworth College in Spokane, Washington on a music scholarship and there she met her husband, Nick Chenoweth. The who were married in 1958. The two moved to Orofino, Idaho and ran a ski shop near Bald Mountain ski area. Later, Helen managed the Northside Medical Clinic while Nick attended law school at the University of Idaho. The two divorced in 1975 and Helen moved to Boise to become the executive director of the Idaho Republican Party. She then went on to serve as Congressman Steve Symms' district director in 1977, and later started her own business, Consulting Associates, and became a noteworthy lobbyist in Boise.

In 1994, Helen won the Republican nomination for Idaho's 1st Congressional District and pledged to serve no more than three terms in the U.S. House if elected. She defeated her Democratic opponent as part of a Republican wave that took over the House for the first time in 40 years. With her victory, she became the second woman (after Gracie Pfost) to represent Idaho in Congress. She was considered one of the most conservative members of the House, opposing any regulation and supporting school prayer. She was also noted for her insistence on being called 'Congressman Chenoweth' instead of 'Congresswoman Chenoweth.'

In 1995 Helen voiced concern that armed federal agents were landing black helicopters on Idaho ranchers' property to enforce the Endangered Species Act, in line with a longstanding conspiracy theory. The Los Angeles Times editorialized that during the campaign she gained national attention by "holding 'endangered salmon bakes' during fundraisers, serving canned salmon to ridicule the listing of Idaho salmon as an endangered species." She was quoted as saying in response, "It's the white, Anglo-Saxon male that's endangered today." Chenoweth remained a controversial and polarizing figure in Idaho politics throughout her career.

Congressman Chenoweth was also a strong critic of the Clinton-Lewinsky scandal and was one of the first to call for his resignation over the affair, although she admitted that she had carried on a six-year illicit romance with a married rancher in the 1980s. Chenoweth was re-elected twice and honored her pledge to only serve three terms. She was succeeded by Butch Otter, a fellow republican, who went on to become Idaho's Governor.