Lazio parted ways with manager Maurizio Sarri in May after finishing ninth in the Italian top flight and losing the Italian Cup final to Inter Milan.
"The club warmly welcomes its new manager and is confident that his experience, professionalism and determination will help the club achieve its sporting objectives," Lazio said in a statement.
Gattuso, 48, previously led Napoli to the Italian Cup title in 2020.
Italy are yet to appoint a permanent manager since Gattuso's departure, with Silvio Baldini the caretaker coach since April.
Media reports have linked Roberto Mancini, who led Italy to the European Championship in 2020, with a return to the national team.
