Koppen was born in Iowa, but attended Whitehall High School in Whitehall Township, Pennsylvania, in the Lehigh Valley region of the state. The school was one of 11 high schools in the highly-regarded East Penn Conference (now known as the 12 school Lehigh Valley Conference), a high school league that has produced a number of NCAA and NFL football stars.
As a senior, he earned All-Area, All-East Penn Conference, and All-State honors, and was named the defensive MVP in the 1997 Kaylee Rotary Bowl. As a junior, he was an All-Conference selection. He also lettered two times each in basketball and track and field.
After the Patriots won Super Bowl XXXVIII that year, defeating the Carolina Panthers, Woody signed with the Detroit Lions, leaving Koppen as the Patriots' starting center. Koppen once again helped them win Super Bowl XXXIX the following year, defeating the Philadelphia Eagles.
Koppen's 2005 season was derailed by a devastating shoulder injury suffered in a game against the Miami Dolphins. In the 2006 season, he returned to his role as the Patriots' starting center, where he is considered one of the NFL's predominant offensive linemen.
On October 12, 2006, the Patriots announced that they had signed Koppen to a five-year, $20 million contract extension, keeping him in New England through the 2011 season.