Warner went to the Green Bay Packers training camp in 1994, but was released before the regular season began. He returned to Northern Iowa and worked as a graduate assistant coach with the football team but he still wanted to get a tryout with an NFL team. When no NFL team would give him a tryout, Warner began playing for the Arena Football League. In 1995, he signed with the Iowa Barnstormers. Warner was named to the AFL's All-Arena first team in both 1996 and 1997. He led the Barnstormers to the Arena Bowl in both 1996 and 1997. Some people consider Warner one of the greatest Arena Football player of all-time.