An eight-year veteran, McCown possesses familiarity with the system employed by offensive coordinator Mike Martz from playing for the coach in 2006 as a member of the Detroit Lions
"We knew, just from my experience with Coach Martz, that we would be on the radar [when Jay Cutler suffered a fractured thumb on Sunday]," McCown said on "The Carmen, Jurko & Harry Show" on ESPN 1000.
McCown's experience appealed to Martz.
"The value for us that I saw is that he's very familiar with what we do," Martz said. "He's not a guy that has to come in and learn the system, learn the numbers, learn the system, learn the route trees and stuff. He's been through that, so he gives us a guy who can go right in there and play."
The quarterback expressed a desire to join the Bears as far back as May, 2010 when the club was searching for a veteran backup quarterback.
McCown spent the 2010 season playing for the Hartford Colonials of the United Football League. The quarterback signed with the San Francisco 49ers on Aug. 17, but was released the following month.
"I still have a huge desire to play and I enjoy playing, especially to reconnect with Coach Martz after being in his offense before," McCown said. "So several factors, another opportunity to play and be around the guys and be part of an organization like that. It's exciting."
McCown spent the first four years of his career with the Cardinals, before spending one season with the Lions. McCown signed with the Oakland Raiders in 2007, and played for the Carolina Panthers from 2008-09.
In 47 games with 31 starts in the NFL, McCown passed for 6,584 yards with 35 touchdowns and 40 interceptions, in addition to a career passer rating of 71.3.
Michael C. Wright covers the Bears for ESPNChicago.com and ESPN 1000. ESPNChicago's Jeff Dickerson contributed to this report.