Izzo attended Rice University from 1992 through 1995 and played linebacker for the football team. He started at the position for three years and in his senior season was named the team's defensive captain.
Izzo started his NFL career with the Miami Dolphins in 1996. He made the team as a special teams ace and in his rookie season played in all 16 of the Dolphins games and made 12 tackles and also block a punt and deflected two punts. Throughout the rest of the late 90's Izzo continued to play as a backup linebacker and special teams coverage wizard. In 2000, he made the AFC Pro Bowl Team as the AFC's special teamer. The next year (2001), he joined the New England Patriots and was voted instantly as a team captain. In part due to his important contributions, the Patriots became Super Bowl Champions that year. In 2002, Izzo was named AFC Special Teams player of the week twice and once again made the AFC Pro Bowl Team as the AFC's special teamer. The next year (2003), he made his first career NFL interception when in the last game of the regular season he intercepted a pass in the Patriots endzone to seal a Patriots completed shutout and 31 -0 victory over the Buffalo Bills... In 2004, Izzo set a career high in tackles with 25 (22 of them solo). On March 6, 2007, Izzo resigned with the Patriots. Since he joined the Patriots in 2001, he has only missed one game and played in 79.