Macklin was a three-year starter at Penn State University. He was selected an All-Big Ten player as a junior in 1998, the year when he led the conference in interceptions with six. As a freshman Macklin briefly played point guard for the Penn State basketball team after the football season had ended.
Macklin signed as a free-agent contract with the Arizona Cardinals in 2004. He scored his only NFL touchdown on a 60-yard interception return for the Cardinals in 2005. He was released by the Cardinals in March, 2007, making him a free agent again.
Washington Redskins
On April 5, 2007, he agreed to a deal with the Washington Redskins. He became a free agent at the conclusion of the season.
St. Louis Rams
Macklin signed with the St. Louis Rams in March 2008. He spent training camp with the team, but was released during the final cuts on August 30.
Kansas City Chiefs
Macklin signed with the Kansas City Chiefs to a two-year contract on November 5, 2008.[3]