The Cardinals may be in need of extra depth in the secondary as they await word on the severity of the knee injury to safety Budda Baker, who often works out of the slot. Cornerback Bene Benwikere has been utilized in that spot by Arizona.
Amerson, who worked out for the Cardinals on Tuesday, spent the offseason with the Kansas City Chiefs after being released by the Oakland Raiders on Feb. 5. The 26-year-old was released by the Chiefs on Sept. 1.
Listed at 6-foot-1 and 205 pounds, Amerson recorded 249 tackles, eight interceptions, two forced fumbles and one fumble recovery in 68 career games with the Washington Redskins (2013-15) and Raiders (2015-17).
The 28-year-old Johnson collected 231 tackles, five interceptions, five forced fumbles and two fumble recoveries in 77 career contests with the Tampa Bay Buccaneers (2012-14), New England Patriots (2015), Carolina Panthers (2016) and Bills (2017).
Also on Wednesday, the Cardinals signed offensive lineman Rick Leonard to the practice squad.
Leonard was a fourth-round selection of the New Orleans Saints in the 2018 NFL Draft after being a two-year starter at Florida State. He spent the preseason with the Saints before being released on Sept 1.
The 21-year-old latched on with the Rams' practice squad before being released on Nov. 6.