The 24-year-old became a free agent last Saturday after La Liga outfit Sevilla agreed to cancel his contract by mutual consent.
After coming through the ranks with Sevilla, Cala broke into the first-team picture in 2009, making his debut in a 1-0 win over Rangers in the UEFA Champions League.
He made 32 appearances in all competitions for Sevilla, and had a spell on loan at Greek outfit AEK Athens in the 2011-12 campaign, though he was later recalled.
Manager Ole Gunnar Solskjaer was busy during the January transfer window, with the likes of Kenwyne Jones, Fabio and Wilfried Zaha all making the switch to the Cardiff City Stadium.
Cala is available for immediate selection, and could face Cardiff's fierce rivals Swansea City in Saturday's derby at the Liberty Stadium.
Cardiff are currently 19th in the Premier League, two points adrift of safety.
