Currently one in 4 children in Wales are overweight or obese when they start school.
The 10 Steps to a Healthy Weight outlines positive actions to help prevent the problem.
Public Health Wales said it wants every child who is born in Wales to get to their fifth birthday at a healthy weight.
The advice focuses on three age ranges - pre conception and pregnancy, 0-2 years and 2-5 years.
It is designed to support professionals and help families across Wales to prevent the growing problem of childhood obesity.
Those who start school with weight problems are more likely to be overweight as a teenager and as an adult, which brings with it a raft of further health complications like asthma, low self esteem and diabetes.
Julie Bishop, director of health improvement at Public Health Wales, said: "Obesity is an important health issue for Wales and tackling this at an early age can have a significant impact.
"We know that obesity is an issue that requires action from across Welsh life.
"There is a role for all agencies, organisations, communities, businesses and of course families to taking action."
The 10 Steps include recommendations like prospective parents getting to a healthy weight before starting a family, giving under fives the chance to play outside every day and limiting their screen time.
Health officials in Wales have launched a 10-step checklist to tackle childhood obesity.