About 2,000 seven to 13-year-olds in the country will have the opportunity to go on the 10-week programme over the next three years.
Families who enrol themselves or are referred by a GP will get advice on healthy eating, physical activity and shopping on a budget from experts hoping to change behaviour and build children's confidence. When the course is finished, follow-up sessions and telephone support will also be available.
The Welsh Assembly said the twice-weekly classes will teach ‘weight management skills’, rather than focus solely on losing weight.
Child health experts at Great Ormond Street Hospital and University College London devised the Mend programme – short for Mind, Exercise, Nutrition ... Do It!
About one in five 13-year-olds in Wales is said to be obese or overweight.
The announcement comes a week after an NHS dietician revealed that children as young as two were being treated for obesity. Clare Baber, a dietician at Gwent Healthcare NHS Trust, last week said she sees a couple of obese two-year olds in her clinic every year.