Pulga, who was in charge of the Sardinian outfit in the 2012-13 campaign, has replaced Diego Lopez following his dismissal after Sunday's 3-1 loss at home to Roma.
A statement on the club's website read: "Pulga returns to to guide the first team.
"The coach has led the first training session this (Monday) morning."
Sunday's loss was Cagliari's fourth in their last five games and dropped the islanders to 15th in the Serie A standings, seven points clear of the relegation zone.
Cagliari president Massimo Cellino defended his decision to sack Lopez with six games to go before the end of the season.
"I had no choice but to do this," Cellino said to Gazzetta dello Sport. "I wish I could have avoided doing this but Lopez gave me no choice."
Pulga, 49, returns to the club just two months after being dismissed as Lopez's assistant by Cellino.
Cagliari, winners of just two games in 2014, visit Sassuolo on Saturday.