According to al-Bahrain al-Yawm, he had been shot by Saudi regime forces on October 17 in al-Qudayh town in Qatif region of the Shia-populated Eastern Province.
Wounded by the gunshot, he was arrested and taken to an undisclosed location, the reports said.
His family and lawyers did not know where he was being held until they learned about his martyrdom a few days ago.
Eastern Province has been the scene of peaceful demonstrations since February 2011. Protesters have been demanding reforms, freedom of expression, the release of political prisoners, and an end to economic and religious discrimination against the oil-rich region.
The protests have been met with a heavy-handed crackdown by the regime. Regime forces have increased security measures across the province.
Over the past years, Riyadh has also redefined its anti-terrorism laws to target activism.