The boy was arrested in late July, accused of intentionally peeing on a carpet in the library of a Koranic school in Bhong city.
When he was released on bail last week, an angry mob from the Muslim majority population attacked Hindu homes and businesses in the Rahim Yar Khan district.
More than a hundred Hindu families are said to have fled the attacks, condemned by Prime Minister Imran Khan.
Blasphemy can carry the death penalty in Pakistan, but no one has been executed for the crime since 1986, according to The Guardian.
However, several people suspected of the crime have been killed by religious fundamentalists.
The eight-year-old is now in custody with the police.
- He still does not understand what his crime was or why he was imprisoned for a week, says a family member to the newspaper.