Robinson suffered an unspecified patella injury during last Sunday's 16-14 victory over the Tampa Bay Buccaneers.
New Orleans also announced the signing of veteran cornerback Chris Carr, who spent the summer and preseason with the Saints.
Robinson, a first-round draft pick out of Florida State in 2010, has had an up-and-down career with the Saints. The 5-foot-11, 191-pounder showed enticing potential early in his career, recording a combined seven interceptions in 2011-12.
But Robinson also struggled to prevent big plays in 2012 and was demoted to a backup role this season after the Saints signed free agent Keenan Lewis.