Dennard was waived by the Patriots earlier this week.
On Tuesday, the Patriots waived Dennard, who started 20 games and recorded five interceptions for New England over three seasons with the team. Dennard played in six games, starting four, during a 2014 season cut short by injury.
The 25-year-old Dennard joins a secondary led by first-team All-Pro Patrick Peterson. Despite the Cardinals' fifth-ranked scoring defense (18.7 points per game) in 2014, the team allowed 259.5 passing yards per game, 29th in the NFL.
The Cardinals selected offensive tackle D.J. Humphries with the 24th pick of the first round of last week's NFL draft.
- Stanley Kay