The 27-year-old spent six months on loan with Napoli during the 2012-13 Serie A season and he has now decided to follow his former Azzurri coach Walter Mazzarri to San Siro.
A statement published on inter.it read: "Rolando Jorge Pires da Fonseca, better known simply as Rolando, has signed for Inter on loan from Porto.
"Born in Cape Verde, the 27-year-old is a naturalised Portuguese citizen. Since beginning his career at Belenenses, he has acquired a wealth of experience at Porto (2008-2013), Napoli and Portugal (U21 and senior teams), and will now further strengthen Walter Mazzarri's defensive options.
"The centre-half is due to start training with the Nerazzurri when they return from their tour of the United States. On behalf of everyone at the club and all our fans, welcome aboard Rolando!"
Rolando played a key role as the Dragons won three Portuguese championships in four years and he lifted the Europa League trophy under Andre Villas-Boas in 2011.
However, he fell out of favour with Villas-Boas' successor Vitor Pereira in January and briefly left the Estadio do Dragao to help Napoli finish second in Serie A.