Lawyer Walid Abu Al Khair was charged with seeking to undermine the state, insulting the judiciary and breaking allegiance to King Abdullah.
A Jeddah court sentenced prominent Saudi rights lawyer Walid Abu Al Khair to 15 years in prison on Sunday on charges that included seeking to undermine the state and insulting the judiciary, the state news agency reported.
Abu Al Khair had been on trial on sedition charges that included breaking allegiance to King Abdullah, showing disrespect for authorities, creating an unauthorised association and inciting public opinion.
The rights activist was also fined SAR200,000 ($53,300), banned from travelling outside the kingdom for another 15 years and had all his websites closed down, the Saudi Press Agency (SPA) said.
Apart from Sunday's conviction, he had been sentenced by a Jeddah court last October to three months in jail for signing a petition in 2011 against the imprisonment of a group of activists demanding political reforms.
Abu Al Khair, the founder and director of an organisation named the Monitor of Human Rights in Saudi Arabia, was critical of a new anti-terrorism law passed by Saudi Arabia at the start of the year which was widely condemned by rights activists as a tool to stifle dissent.
The anti-terrorism law states that terrorist crimes include any act that "disturbs public order, shakes the security of society, or subjects its national unity to danger, or obstructs the primary system of rule or harms the reputation of the state".
In the past year Saudi authorities have been criticised by international rights groups for jailing several prominent activists on charges ranging from setting up an illegal organisation to damaging the reputation of the country.
The world's top oil exporter has regularly dismissed criticism of its human rights record by Western countries and campaign groups.