There are two stories related to the origin of the name. One is that found in the official books and documents where Postira has been mentioned in the far 1347 under the name Postirna (from lat. pastura = pasture), whilst the second one, appealed to oral tradition, associate that place with women from the neighbouring village Dol who came to Postira to wash and spread out (prostirati in local dialect) their laundry.

Postira was established in 16th century whilst the first inhabitants were people from Dol and Poljice who moved out of their villages. Numerous stone houses in the port testimonies about the former Brač landowners; among them stands out the Lazanić family’s castle in which Croatian poet Vladimir Nazor (1876 – 1949) was born. The Parish Church built in the middle of 16th century is called after John the Baptist whilst under it have been found remains of an early Christian basilica from 6th century. Even other archaeological sites witnessing the long history of Postira: Mirje on the Mali brig hill where an early Christian monastery complex has been found as well as Lovrečina, one of the most beautiful sand beaches where the early Christian church from 5th/6th century is located.