The 5-foot-11, 245-pound Sharpton has played five seasons in the NFL, the first four with the Houston Texans and last year with the Chicago Bears.
He has appeared in 47 games, 21 as a starter.
The Cardinals also signed second-round pick Markus Golden and fourth-round selection Rodney Gunter to four-year contracts Wednesday.
Golden, a defensive end from Missouri, was the 58th overall pick. Last season, he had 78 tackles, 10 sacks, three fumble recoveries and three forced fumbles in 13 games.
Gunter, a linebacker from Delaware State, was the 116th overall selection.
All content copyright ©2015 Daily Journal, a division of Home News Enterprises unless otherwise noted.