Sulaiman al-Subaie, 25, who grew popular in his homeland for his posts on video-sharing app Keek, reportedly joined the most radical group fighting in Syria, the Islamic State of Iraq and the Levant (ISIL), last August.
"The situation in Syria is not as portrayed in the media," Subaie said in a rare interview aired on Saudi television late yesterday.
"What is amazing is that Saudis are killing fellow Saudis in the fighting between ISIL and Al-Nusra Front," said the Al-Qaeda franchise in Syria.
Fierce clashes between ISIL and opposition fighters broke out in early January, after accusations that the radical group was abusing both civilians and rival rebel forces.
The fighting has left hundreds dead and created openings for regime advances in some areas.
Subaie said in his "confessions" that the death of his brother, a jihadist, as well as "pictures of dead Syrian children" had prompted him to join the war.
He wanted to join Al-Nusra Front but "upon my arrival, I was told that I have now become a member of ISIL," he said.
Subaie decided to quit the group after realising that his Twitter account, followed by thousands in Saudi Arabia, was being used to broadcast "messages inciting" violence against rulers and clerics in Saudi Arabia.
He fled back to Turkey and returned to the kingdom, where he is being held.
There are no official figures on the numbers of Saudis who have joined jihadist ranks in Syria, but they are estimated at several hundred.
But King Abdullah last month decreed jail terms of up to 20 years for citizens who travel to fight abroad, as the country struggles to deter young Saudis from becoming jihadists.
