After the death of Alexander, the city remained in Egyptian hands from 209 BC to 197 BC, under the dynasty of Ptolemaios, and with the conclusion of the Apamea treaty, was handed over to the Kingdom of Rhodes, together with the other cities of Lycia. From 190 BC to 160 BC it remained under Rhodeian hegemony, but after 160 BC it was absorbed into the Lycian confederacy under Roman rule. Phaselis, like Olympos, was under constant threat from pirates in the 1st century BC, and the city was even taken over by the pirate Zekenites for a period until his defeat by the Romans. In 42 BC Brutus had the city linked to Rome. In the 3rd century AD, the harbor fell under the threat of pirates once again. So it began to lose importance, suffering further losses at the hands of Arab ships, until totally impoverished in the 11th century. When the Seljuqs began to concentrate on Alanya and Antalya as ports, Phaselis ceased to be a port of any note.

There was a temple of Athene at Phaselis, where the lance of Achilles was exhibited. It was the birthplace of the poet and orator Theodectes. It was also renowned for its roses, from which the essence was extracted.