The state security court in Amman found Zaki Bani Rsheid, deputy head of the Brotherhood in Jordan, guilty of making statements "likely to damage relations between the kingdom and a foreign country".
Rsheid, 57, made no comment after the verdict but his lawyer Saleh al-Armuti said he planned to appeal.
The Islamic Action Front, political wing of the Brotherhood's Jordanian branch, in a statement denounced the verdict as going against "individual liberties and the freedom of expression".
It was "a clear and negative political message", the IAF said.
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Rsheid was arrested in November after he criticised the UAE for blacklisting more than 80 Islamist groups including the Brotherhood.
In comments published on his Facebook page, Rsheid described the UAE as "the prime godfather of terrorism", and accused the energy-rich Gulf state of serving US and Israeli interests in the region.
Jordan is a close ally of the UAE and both nations are part of the US-led campaign against the Islamic State group that controls swathes of territory in Iraq and Syria.
Organisations blacklisted by the UAE include Al-Qaeda, IS, Yemen's Shiite Huthi militia and the Muslim Brotherhood -- which was formed in Egypt in 1928 and has branches across the region.
The Jordanian branch of the Brotherhood is the main opposition force in the kingdom and has wide grassroots support.