The league announced Friday that Nelson will be suspended without pay for the Bills' regular-season games against the Dolphins, Packers, Patriots and Jets. He can return to the active roster Oct. 4 and play the following weekend against the Jaguars.
Nelson had 17 catches for 156 yards and a touchdown in 12 games as a rookie out of Southern Mississippi last season.
The Bills were already short-handed at tight end after Derek Schouman hurt his knee in Thursday's 34-21 preseason victory over the Indianapolis Colts. Nelson is eligible to participate in all preseason practices and games.
Nelson's agent, Joel Segal, declined comment.