Rivers was released by the Bills back in February in a move that cleared $1.7 million in available cap space.
Rivers, 28, is a former first-round pick of the Cincinnati Bengals back in 2008. He spent five years with the Bengals before was traded to the Giants in return for a 2012 fifth-round pick that ultimately became S George Iloka.
Last year, Rivers appeared in 12 games for the Bills and recorded 16 tackles. Pro Football Focus has him down for playing 192 snaps to go with a below average rating.