Zeman quit his post at the Serie A strugglers on Tuesday, ending his second spell of the campaign at the Sardinian club, and Festa has assumed control for the closing weeks of the season.
Festa – who started his playing career at Cagliari – will be assisted by David Suazo and Gustavo Aragolaza, Gianfranco Ibba and Giomaria Ruiu as he looks to lift the club out of the bottom three.
With seven games to go, Cagliari are 19th in the league table and nine points from safety.
Festa, 46, is the club's third different coach of the season, with another fomer fans' favourite Gianfranco Zola having endured a torrid 11-game spell at the helm.
‘So many times when we played Manchester United, arguments would start before the first whistle had even blown – the players would try to kill each other with their eyes’ Former Arsenal star remembers famous Premier League rivalry
Bizarre Jose Mourinho statement aims to pre-empt punishment after Fenerbahce boss clashes with Galatasaray counterpart
