The United States sent 29 Saudis back home this year after negotiating a framework agreement with Saudi Arabia for the return of its citizens.
Saudi officials had said they were reviewing whether they should face charges in their homeland.
Mansour al-Turki, an interior ministry spokesman, said: "Nine of them have been released. They were investigated and we didn't find any wrongdoing in relation to local laws. There is no evidence [against them]."
He said that there was no agreement with Washington obliging Saudi Arabia to keep them incarcerated. He gave no more details.
About 95 of the 450 men still held at Guantanamo are Saudi citizens and the government has said it hopes to bring all of them back within a year.
Many of the men held at the prison in Cuba were captured in Afghanistan in the US-led war to oust the Taliban after al-Qaeda carried out the attacks against the US on September 11, 2001.
Two Saudis are among 10 Guantanamo prisoners who have been charged with war crimes in a tribunal system which the US supreme court struck down in June.
Public anger over the treatment of the Saudi detainees has been high.
Two Saudis were among the three prisoners who hanged themselves in June at the prison, which lies outside the jurisdiction of international law.
Many Saudis suspect that they died from maltreatment.
The authorities have organised a wedding for one of the returnees and have supported the education of their children.