Terms of the deal were not disclosed.
Byrd, one of the most highly sought after players in the 2014 free agent class, was selected with the 42nd overall pick of the 2009 NFL Draft by Buffalo, where he spent the first five seasons of his career.
The three-time Pro Bowler missed the first five games of the 2013 season with an injured foot. He appeared in the final 11 games of the season, totaling 48 tackles, four interceptions and one forced fumble.
"We had hoped for the opportunity to pursue Jairus Byrd," said Saints general manager Mickey Loomis. "After meeting with him, we are excited that he will become a member of the New Orleans Saints. We think that his play-making abilities will be an excellent fit with what we are trying to accomplish with our defense and in our secondary."
Over 73 career games, Byrd has 356 tackles and 22 interceptions, nine of which came in his 2009 rookie campaign.