It was in 273 BC that Rome made Paestum a colony. Like her neighbor Velia, her role was in need of providing ships and sailors to the Romans.
It was thus probably involved near Rome during the 1st Punic War. During the Second Punic War, the Paestans allowed the Romans besieged in Taranto by Hannibal to resist, providing ships loaded with wheat.
Rewarded, the city had the right to strike its own currency, on which we find the acronym “PSSC” (Paesti Signatum Senatus Consulto)

During the Roman period, despite the crisis that followed the war against Hannibal, economic and cultural activities flourished. New public buildings were built, such as the amphitheater, the forum, the Temple of Peace and the gymnasium.
The Romans modified the organization of the city, substantially changing the urban fabric, especially in the area between the two sacred areas, where was created the forum that replaced the agora, and was surrounded by small businesses and small temples.
Ramparts were erected, 5 to 7 meters thick, and 5 km long.
Private dwellings also testify to this vast urbanization, which does not seem to have been compromised by the construction of two great Roman roads: the Apian Way and Via Popilia which passed far from Paestum.
The surrounding territory was also adapted by the Romans, where traces of the agricultural divisions were found, necessary to distribute the land to the new settlers.

After becoming a municipality after the Social War (during the 1st century BC), it experienced a revival of vitality in the early days of the imperial era. Then its existence does not seem to have been disturbed by major events until the beginning of the fourth century of our era, when gradually the decay of the Roman Empire brought Paestum into decline, slow but inexorable.