Knight was placed on the Falcons' practice squad injured reserve Tuesday, D. Orlando Ledbetter of the Atlanta Journal Constitution reports.
Knight suffered an undisclosed injury and will now most likely spend the remainder of the season on injured reserve. Look for more updates to come once information is made available.
Knight was waived by the Cardinals on Friday, Josh Weinfuss of ESPN reports.
While he had a great college career at both Oklahoma and Texas A&M, Knight was seen as a long shot to make the team's final roster. After he completed just two of 12 passes for 19 yards and an interception in Thursday's preseason finale against the Broncos, Knight's time was up in Arizona.
Knight will play the second half of Thursday's Hall of Fame Game versus the Cowboys, Darren Urban of the Cardinals' official site reports.
Knight is merely a camp body in Arizona, but head coach will give veterans Carson Palmer and Drew Stanton that evening off, handing the keys of the offense to the remaining reserve quarterbacks. After Blaine Gabbert takes on first-half duty, Knight will take over in the second half. In four seasons between Oklahoma and Texas A&M, Knight completed 55.5 percent of his passes, averaged 167 yards per game and tallied a 44:26 TD:INT ratio in 35 contests.