The 29 year old international has made 148 appearances while at Benfica but was limited to gametime last season after dropping to third choice behind Cesar and Roberto.
He did manage to help the club to Portuguese League Cup, saving a penalty in the final to secure a 2-1 win in what looks like will be his final game for the team.
It is understood that Moreira has already said his goodbyes to team-mates at Estadio de Luz and is bound for south west Wales after agreeing to join Swansea.
A rough translation of the Abola.pt article: "After Quim, Mantorras and Nuno Gomes Moreira leave, another important part of long-time squad Benfica exits Estadia de Luz with the destination already certain: Swansea, a club promoted to the Premiership, the main league of England.
It was a surprise when the news came to his companions and the farewell was emotional. Moreira, who was on stage in Nyon, Switzerland, with the squad of the incarnate, should meet up quickly with his new squad in order to get to work, preparing a special season for the British club.
The Portuguese international goalkeeper, 29, arrived at Benfica in 1999, coming from the Willows, even at the age of junior and was on the B team before being promoted to the first squad, where he quickly became a great hope and one of the most loved players among fans. 148 games later, he left the club in the Light, to embrace the first challenge in the already long career abroad."
Full link: http://www.abola.pt/nnh/ver.aspx?id=274101
Benfica's new signing Nolito told AFP (translated): "I did not know, colleagues commented to me (about Moreira's exit). I've been with him recently, but it's always a sad farewell. He has chosen what he thinks is best, he knows what we do and we must continue to prepare for a strong season."
Signing Moreira would be seen as somewhat of a coup for Swansea; a Portuguese international, the stopper has impressed over the years for Benfica and would seem a more than adequate replacement – on paper – for the outgoing Dorus de Vries.