Yehya Hussein Mohammad al-Dailami, 40, was given the death penalty for “making contacts with a foreign country, namely Iran,” said judge Najib Qaderi.
He was also accused of supporting a rebellion by members of Yemen’s Zaidi minority, which has left hundreds dead in fighting between insurgents and security forces.
The state security court also sentenced another Zaidi defendant, Mohammad Ahmad Muftah, to eight years in prison for supporting the revolt.
A defense lawyer said he would appeal the sentences.
The Zaidis are a Shiite Muslim sect dominant in northwestern Yemen but in the minority in the mainly Sunni country.