Widseth was born in Gonvick, Minnesota in 1910. He played high school football in McIntosh, Minnesota and began his college football career at the Northwest School of Agriculture (later renamed University of Minnesota, Crookston) where he graduated in 1932. Widseth next enrolled at the University of Minnesota where he played football for Bernie Bierman's great Minnesota Golden Gophers football teams of the mid-1930s. The Golden Gophers compiled a record of 23-1 during Widseth's three seasons on the team from 1934–1936. Widseth reportedly "'lived' in enemy backfields and was unquestionably the pillar of strength in the Gopher line" during a period in which they claimed three consecutive national championships. The only game the Golden Gophers lost during Widseth's three years as a starter was a 6-0 loss to Northwestern in 1936. Minnesota had a 28-game winning streak when they went to Evanston for a Halloween Day game against Northwestern. The game was scoreless when Widseth tackled a Northwestern player, and the referee accused Widseth of "slugging" the Northwestern player. After a 15-yard penalty was assessed, the ball was placed at Minnesota's one-yard line, and Northwestern scored a touchdown for the only points of the game. Widseth was a member of FarmHouse fraternity.