The shakeup affects some of the country's largest state-controlled companies: oil firm Eni, energy company Enel, industrial giant Finmeccanica and the Italian postal service.
Emma Marcegaglia, ex-chief executive of employers' federation Confindustria, takes over at Eni, while Patrizia Grieco, head of tech firm Olivetti, will be the new boss at Enel.
Gianni de Gennaro, already acting chief at Finmeccanica, was confirmed in his job. And Luisa Todini, a board member at public TV station RAI, takes the reins at the postal service.
All four bosses will have their gross annual salaries capped at €238,000, the same pay the country's president receives.
Prime Minister Matteo Renzi, who promised the pay cap when his government took office in February, has said he is looking to cut €500 million from executive salaries at state-run companies.