Morrison told reporters in Canberra on Thursday that his decision to reduce the number of government departments from 18 to 14 from Feb. 1 would "bust bureaucratic congestion and improve decision making."
Four new "mega-departments" will be the Department of Education, Skills and Employment; the Department of Infrastructure, Transport, Regional Development and Communications; the Department of Industry, Science, Energy and Resources; and the Department of Agriculture, Water and the Environment.
Despite the shake-up, the biggest to the public service since 1987, Morrison said there would be no change in the ministers responsible for each portfolio.
The changes, not expected to generate significant budget savings, were about "better services on the ground" rather than saving money, according to the prime minister.
"Australians should be able to access simple and reliable services, designed around their needs," he said.
"Having fewer departments will allow us to bust bureaucratic congestion, improve decision-making and ultimately deliver better services for the Australian people. The new structure will drive greater collaboration on important policy challenges."
The announcement comes more than a year after Morrison was chosen to lead the governing Coalition.