Cooper was promoted from Atlanta's practice squad to the active roster Friday, D. Orlando Ledbetter of The Atlanta Journal-Constitution reports.
Cooper signed a two-year deal with the Falcons in April but was waived Aug. 31 after collecting 14 tackles and zero takeaways during the preseason. The 25-year-old defensive back has yet to make his NFL regular-season debut, but he may be afforded his first opportunity Sunday when Atlanta takes on Tampa Bay's No. 1 passing offense.