The runestone first surfaced in the autumn when church authorities in Vallentuna excavated an area around the church in order to lay new cables.
But the historical artefact's runic inscriptions were covered in mud and earth and the rare find went unnoticed for several months.
Only after an extended period of spring rains did staff at the church discover that one of the rocks used to mark out the boundaries of the church car park was most likely a Viking Age gravestone.
Though part of the first word is missing, archaeologist and runic expert Lars Andersson from Stockholm County Museum was able to decipher most of the text, which read: "[...]fr raised this stone in memory of his father, Frösten."
"To read something that nobody else has read for 1,000 years is almost a religious experience," said Andersson in a museum statement.
Archaeolgists estimate that intact runestones of this kind are discovered at most once every decade.