"We are excited about acquiring Jabari," Saints head coach Sean Payton said in a statement released by the team. "He brings speed and cover ability to the position. He has come into this league and quickly has established a reputation for himself, and we are very pleased with this addition to our team."
Greer, 27, spent the past five years with the Buffalo Bills, starting 23 games over the past two seasons.
"Jabari is a young and energetic corner and will fit in nicely into our defensive backfield," Saints general manager Mickey Loomis said in the statement. "He's an aggressive player and has outstanding speed and athleticism and translates the skills very well to the football field."
Greer has four career interceptions, including two last season that he returned for touchdowns. He missed the final six games last season because of a knee injury.
The Associated Press contributed to this report.