Bahrain activist Nabeel Rajab loses final appeal against imprisonment
Rajab, a high-profile rights activist who is already serving a two-year term in another case, was first handed the sentence in February by a lower court and an appeals court confirmed it in June.
The Supreme Court's verdicts are final and cannot be challenged.
Rajab, a leading figure in the 2011 protests against the Gulf state's Sunni-led monarchy, was convicted of insulting the state by "deliberately disseminating", false and malicious news on social media.
He was also convicted of criticising the Saudi-led military campaign in Yemen and publicly offending a foreign country, a reference to Saudi Arabia.
The court convicted him of endangering Bahrain's military operations in Yemen.
Manama is part of the Saudi-led coalition that has been fighting the Iran-aligned Houthi rebels since March 2015.
He also tweeted criticism of the Bahraini government's treatment of prisoners.
In January this year, the same court upheld a two-year imprisonment against Rajab after convicting him of press statements critical to the government.
Bahrain, with a large Shia community, is located between regional rivals Saudi Arabia and Iran and has been ruled for more than two centuries by the al-Khalifa dynasty.
Authorities have jailed dozens of high-profile activists and disbanded both religious and secular opposition groups since Shia-led protests demanding political change erupted in 2011.
They have stripped hundreds of those convicted of their citizenship, leaving many stateless.