The Briton, who has been identified as Robert Douglas Semple, 64, was released by United Arab Emirates forces.
The freed hostage had been working as a petroleum engineer in the Yemeni province of Hadramawt when he was kidnapped in February 2014.
The UAE forces were based in Yemen's main port city of Aden, according to the state news agency WAM. The Yemeni agency reported that he had been held by al-Qaeda for 18 months. Mr Semple was taken to the Yemeni port city of Aden before being flown to Abu Dhabi by military plane on Saturday night, it added.
He has been able to talk to his wife by phone, and will leave for Britain once all the necessary medical checks have been carried out.
The WAM news agency's statement did not say where in Yemen Semple had been held, or provide any details on the rescue operation. Abu Dhabi Crown Prince Sheikh Mohammed bin Zayed-al Nahyan spoke to Prime Minister David Cameron to confirm the release yesterday, the agency reported.