The late dramatics came after Jacksonville rookie receiver Justin Blackmon had four catches for 48 yards and a touchdown. It was the first NFL appearance for Blackmon, who staged a contract holdout before signing shortly before the start of the exhibition season.
Chase Daniel threw two touchdown passes in the second half for New Orleans, the second of them a 24-yarder to Travaris Cadet that gave the Saints the lead in the fourth quarter.
Palmer then drove the Jaguars 74 yards in 12 plays to the winning score.
Jacksonville improved to 2-0 in exhibition play while the Saints are 1-2.