At the inaugural Belk Bowl held in Charlotte on December 27, 2011, Amerson broke the record for the most interceptions in a season by an Atlantic Coast Conference competitor.

He also participated at NC State's Pro Day and made up the three-cone drill and short shuttle while also improving on his combine numbers in the vertical and broad jump.

[15] He made his professional regular-season debut and started the Washington Redskins' season-opener against the Philadelphia Eagles, making four combined tackles and a pass deflection in a 33–27 loss.

[16] During a Week 9 matchup against the San Diego Chargers, he tied his season-high of six combined tackles, made a pass deflection, and intercepted Philip Rivers in a 30-24 victory.

[17] He finished his rookie season with 48 combined tackles (40 solo), ten pass deflections, two interceptions, and a touchdown in 16 games and eight starts.

Head coach Jay Gruden named him a starting cornerback, opposite DeAngelo Hall, to begin the regular season.

[18] Amerson started his third season as the fourth cornerback on the Washington Redskins' depth chart behind DeAngelo Hall, Bashaud Breeland, and Chris Culliver.

[24] On November 29, 2015, he made two solo tackles a season-high six pass deflections, and intercepted Marcus Mariota in a 24–21 win over the Tennessee Titans.

[26] During a Week 15 matchup against the Green Bay Packers, Amerson recorded six solo tackles, three pass deflections, and intercepted Aaron Rodgers in a 30-20 loss.

[27] On January 3, 2016, he made two solo tackles, deflected a pass, and intercepted Alex Smith, returning it for a 24-yard touchdown, for his fourth pick of the season during a 23–17 loss to the Kansas City Chiefs.

Amerson finished his first season with the Raiders with a total of 60 combined tackles (55 solo), 26 pass deflections, four interceptions, and a touchdown in 14 games and 12 starts.

The following game, Amerson recorded a season-high eight combined tackles, three pass deflections, and intercepted Atlanta Falcons' quarterback Matt Ryan during a 35-28 loss.

[36] He played in six games with five starts, recording 21 tackles, two passes defensed, and one interception, which came off Russell Wilson in a Week 17 loss to the Seattle Seahawks.

[37] Amerson is childhood friends with wide receiver Keenan Allen, who was also selected in the 2013 NFL draft by the San Diego Chargers.