The N.F.L. suspended Josh Shaw, an injured defensive back on the Arizona Cardinals, through at least the end of next season for betting on football games this year, the first such penalty in more than two decades.

The league said its investigators found no indication that Shaw used inside information or compromised any game, and his coaches and teammates were unaware that he was placing bets on N.F.L. games.

Still, the league took a hard line with Shaw, who cannot apply for reinstatement until after Feb. 15, 2021.

“The continued success of the N.F.L. depends directly on each of us doing everything necessary to safeguard the integrity of the game and the reputations of all who participate in the league,” Commissioner Roger Goodell said in a statement. “If you work in the N.F.L. in any capacity, you may not bet on N.F.L. football.”