According to the Gulf Center for Human Rights, Mohammed al-Ghamdi’s account on X had only nine followers.
“Saudi courts are increasing their repression and publicly exposing their hollow promises of reform,” said Lina Al-Hathloul, monitoring and communications head of the rights group ALQST.
“How can the world believe the country is reforming when a citizen will be beheaded for tweeting to an anonymous account with less than 10 followers?”
Saudi Arabia faces frequent criticism for its widespread use of the death penalty, with 147 people executed last year, according to an AFP tally.
So far this year, 94 people have been hanged.
State media reports do not mention the method of execution, but beheading has been common in the past.