The former Ghana international arrived in Castile–La Mancha on Sunday.
Muntari will wear the Alba shirt till the end of the season.
The 34-year-old joined on a free transfer after leaving Deportivo La Coruna at the end of last season.
His rich experience having played for Udinese, Portsmouth, Sunderland, Pescara and Al Ittihad of Saudi Arabia will be crucial for his new side.
Muntari won the UEFA Champions League with Inter Milan in 2010 under Jose Mourinho and also played for rivals AC Milan.