Bethel has earned three Pro Bowl selections as a member of special teams for the Arizona Cardinals
The 27-year-old, who visited the Falcons on Wednesday, is expected to provide depth to a secondary that features Desmond Trufant and Robert Alford. Fellow cornerbacks Brian Poole, Blidi Wreh-Wilson and Marcelis Branch are also on the roster.
Bethel has recorded four interceptions -- with three returned for touchdowns -- in his last three seasons.
He has collected 185 tackles and four interceptions in 96 career contests with Arizona. Bethel has yet to miss a game since being selected by the Cardinals with a six-round pick in the 2012 NFL Draft out of Presbyterian College.
The acquisition of Bethel represents the biggest free-agent offseason move thus far for Atlanta. The Falcons also signed former San Francisco 49ers guard Brandon Fusco and re-signed defensive end Derrick Shelby.