Harö has probably been populated since the Middle Ages. The oldest known map dates from the 1640s and shows three farms at what is today the town of Harö in the north of the island. However, archaeological investigations show that the village previously lay about one kilometer further south by the lake called the Old Town Grass. When the land raising ends of the lake from the bay called Hamnviken, the harbors had to move the village to gain access to a sheltered harbor.

Harö had rich fishing waters and good conditions for hunting and farming, which caused the village to grow. At the turn of the 1840s there were a total of 19 farms in the village, of which 14 were allocated new plots along the west coast of Harö at Lerviken, Skarpslätt and Nöttnäs, and to Storö, which lies north of Harö. Despite the profound changes of the changeover, Harö maintained its position, in 1909 there were still nine farms in the village. Now a hundred years later, the village consists of twenty settled plots.