After his first venture with professional football ended, Nevers joined the St. Louis Browns of Major League Baseball. He appeared in 12 games, 11 as a pitcher, for the 1926 Browns, compiling a 2–4 win-loss record and a 4.46 earned run average (ERA) in 74-2/3 innings pitched. At the plate, he had a .185 batting average in 27 at bats. Nevers threw the ball in an unusual underhand delivery. On August 13, 1926, in the highlight of Nevers' 1926 season, he pitched a complete game victory over the Detroit Tigers, giving up eight hits and two runs against a lineup that included Hall of Famers Ty Cobb, Heinie Manush, Charlie Gehringer, and Harry Heilmann, and Bob Fothergill who hit .367 that year.
In September 1926, Nevers left the Browns to play professional football for the Duluth Eskimos of the National Football League (NFL). Nevers' childhood friend Ole Haugsrud owned the Eskimos. The 1926 Eskimos, with a 16-man roster, played a 29-game schedule and compiled a 19–7–3 record. Nevers reportedly played 1,714 minutes out of a possible 1,740 minutes that year. Highlights of Nevers' 1926 season included the following:
Out of the 29 games played by the Eskimos in 1926, 14 are considered official by the NFL; in those games, Nevers scored 71 points on eight touchdowns, 11 extra points, and four field goals. At the end of his rookie season, Nevers was a consensus pick for the fullback position on the 1926 All-Pro Team, receiving first-team honors from Collyer's Eye magazine, the Chicago Tribune, and the Green Bay Press-Gazette.
Nevers was married to Mary Elizabeth "Mae" Heagerty in February 1926 in San Francisco.