The experienced right-back, who featured in all three of Portugal's group games at the 2014 FIFA World Cup, including the tie with Germany, has put pen to on a contract lasting until 30 June 2015.
The 30-year-old came through the youth ranks with Benfica SL, making his professional debut with the capital city side in 2003. He then went on to enjoy stints with Portuguese outfits Gil Vicente FC, SC Braga and Sporting Clube de Portugal before moving to Valencia CF in the summer of 2012.
"His international experience speaks to his qualities," said Hannover sporting director Dirk Dufner. "Joao Pereira featured for Portugal in the 2014 FIFA World Cup and UEFA EURO 2012, has played in the UEFA Champions League and UEFA Europa League as well as making over 230 appearances in the Portuguese and Spanish top flights. That he's chosen to join Hannover 96 and take on the challenge of the Bundesliga delights me."
Head coach Tayfun Korkut was also pleased to bolster his squad with a back-up for Japanese international Hiroki Sakai. "We wanted to bring in another right back for the second half of the season. Joao Pereira brings with him a lot of experience and first-class qualities to help us in the short-term."