Keith Smith debuted for the Detroit Lions of the NFL in 2004. #23 was a solid backup for Detroit into 2008. In 2007, he returned an interception 64 yards for a touchdown.
San Francisco 49ers
As a free agent following the 2008 season, Keith Smith signed with the San Francisco 49ers. He had five tackles for them on 2010.
On June 18, 2010, San Francisco released Smith.
Omaha Nighthawks
Keith Smith was signed by the Omaha Nighthawks of the UFL on June 29, of 2011. With a #25 jersey on his back, Smith remained with Omaha through all of 2011.