Smith is a 10-year veteran who most recently played with the Cincinnati Bengals. He played in only two games last year after suffering a season-ending torn biceps.
In addition to the Bengals, the 6-foot-4, 250-pounder has played for the Tampa Bay Buccaneers, Philadelphia Eagles and Cleveland Browns, primarily as a blocking specialist. He has 163 catches for 1,473 yards and 13 touchdowns in his career.
Smith will compete for a backup role behind top Saints tight ends Benjamin Watson and Josh Hill. He'll compete with fellow veterans Orson Charles and Kevin Brock, both of whom also previously played in Cincinnati.
Tabb, a 6-3, 250-pounder from North Carolina, was waived injured. He could return to the Saints' injured reserve list if not claimed by another team.
Tabb appeared to suffer a knee or leg injury while landing hard after leaping for a ball in the end zone. He was in obvious pain as trainers attended to him.