Frazier was part of a revamped staff announced Tuesday by Marvin Lewis, who was hired earlier this month to replace the fired Dick LeBeau.
Frazier, 43, was a cornerback for the Chicago Bears from 1981-86 and coached three seasons at Illinois before joining the Eagles.
"Their guys have played outstanding football," Lewis said of Frazier's Eagles in talking with the Cincinnati Enquirer. "My attraction is the style of defense they have played, and I think this is going to be an outstanding fit."
Frazier will be the first African-American coordinator in the Bengals' 35-year franchise history.
"The fact that Marvin is head coach, someone who has been successful, someone who does his homework, the situation in Cincinnati is not much different than it was in Philadelphia four years ago," Frazier told the paper.
While Lewis went outside the organization for a defensive coordinator, he elected to retain Bob Bratkowski as his offensive coordinator. Bratkowski will enter his third season with the Bengals.
Other notable assistants retained by Lewis include offensive line coach Paul Alexander, running backs coach Jim Anderson, and defensive backs coach Kevin Coyle.
Ken Zampese, the passing game coordinator of the St. Louis Rams the last two seasons, is the new quarterbacks coach. He replaces Ken Anderson, who has spent 16 years with the Bengals as a player, 10 as quarterbacks coach and six as a broadcaster.
The Bengals also named Alex Wood wide receivers coach, Jay Hayes defensive line coach, Ricky Hunley linebackers coach, Darrin Simmons special teams coach, Chip Morton strength and conditioning coach, and Kurtis Shultz assistant strength and conditioning coach.
Lewis will try to turn around a team that has not made the playoffs since 1990. Cincinnati is a mere 19-61 over the last five seasons.