The units at four major Scottish hospitals will assess and treat people who have suffered a major trauma, including serious head injuries and knife wounds.
Health chiefs say the availability of immediate specialist care could save up to 40 lives every year.
The four bases will be operational from 2016 at Edinburgh Royal Infirmary, Ninewells Hospital, in Dundee, Aberdeen Royal Infirmary and the new Southern General Hospital in Glasgow.
Of around 5,000 people seriously injured in Scotland every year, 1,100-1,200 cases are defined as "major trauma", which is defined as multiple injuries to the body, a serious head injury, knife and gunshot wounds or a spinal injury.
Trauma patients also include those who have been severely burned or require a limb amputation.
Where possible these patients will be taken to one of the four centres and treated by a team with specialist facilities.
Local hospitals will continue to care for people with less serious injuries, such as fractures and minor head injuries, and will still deal with some more serious trauma cases.
Health Secretary Alex Neil said: "By ensuring patients have timely access to the highest level of expertise and medical facilities, this could save up to 40 lives each year."
"These changes are part of plans to enhance major trauma services across Scotland and deliver the very best possible outcomes for people who experience life-threatening injuries.
"The national network will involve the Scottish Ambulance Service, specialist major trauma centres and local hospitals working together to make a real difference to the lives of seriously-injured people in Scotland.
Peter McCarron, from Kelty in Fife, suffered multiple injuries to his spine and pelvis in an accident when working as a mechanical fitter 11 years ago and spent three months in Queen Margaret Hospital in Dunfermline.
The 53-year-old used his experience of major trauma care as a patient representative on the Scottish Trauma Audit Group steering group to help shape the new plans.
He said: "The care I received on the day of the accident saved my life. I've always had the idea that if you were taken to hospital, then you were going there to be fixed as something in the body was broken.
"I'm glad to say that they were able to fix me, but only to a point. Because people are all different, then it follows that all traumas are different. As people are individuals, then each trauma has to be treated to what the individual needs and this adds to the complex methods needed to ensure the patient will not only survive but have a reasonable standard of life afterwards.
"The amount of different staff from a large variety of departments is needed to not only help the patient survive in the first instance, but to help them develop and to cope so that the trauma doesn't then rule their lives."
Dr Dave Caesar, clinical director of emergency medicine at NHS Lothian, said: "The Royal Infirmary of Edinburgh Emergency Department is the biggest adult receiving unit in Scotland and thrives on delivering true emergency critical care to such a high number of patients.
"It is an exciting time for trauma medicine in Edinburgh and we are pleased to have been selected as one of Scotland's four major trauma centres.
"We believe our department offers the opportunity to improve the practical, clinical and non-technical skills required to manage these challenging patients."