Irish children are now the 58th most overweight globally and rank eighth in Europe.
A major worldwide league table of 200 countries published in the 'Lancet' today also reveals that Irish girls rank 79th for obesity and boys are 98th.
It comes as Health Minister Simon Harris announced €5m towards the national obesity strategy in 2018.
The figures show that worldwide there has been a more than tenfold increase in the number of children and adolescents with obesity in the past four decades.
In 2016, 50 million girls were obese and 74 million boys, according to the global analysis of trends in child and adolescent obesity.
Rates of child and adolescent obesity were highest (above 30pc) in some islands in Polynesia, and were around 20pc or higher in the US and some countries in the Middle East and North Africa.
Despite the increase in child and adolescent obesity, globally more children remain moderately or severely underweight than obese, with a majority in south Asia.
The study, led by Imperial College London and the World Health Organisation (WHO), is published to mark World Obesity Day.
Prof Cecily Kelleher, of the UCD Institute of Food and Health, oversaw the submission of Irish figures.
Overweight and obesity rates in Ireland are estimated to be 41.8pc in boys and 39.1pc in girls.
Girls in Ireland rank eighth in Europe for levels of obesity and boys are in 15th place. Worldwide, Ireland has decreased in ranking positions over time between 1975 and 2016 in terms of childhood overweight and obesity prevalence.
However, it has scaled up at the European level.
One of the study's main conclusions is that "obesity rates have plateaued in higher income countries, although obesity levels remain unacceptably high".
This stabilisation in overweight and obesity rates is also seen among Irish schoolchildren.
However, figures still remain high.
Overweight and obesity rates in Ireland in 2008 were at about 20pc, whereas results from the two latest rounds - 2012 and 2015 - show the prevalence of overweight and obesity among children aged six to seven years old was 17pc.
Excessive weight gain in childhood and adolescence is associated with a higher risk, and earlier onset, of chronic diseases such as type 2 diabetes, worse psychosocial and educational outcomes, and lifelong harms since weight loss is hard to achieve.
Average child and adolescent BMI remains high in many high-income countries in North America and Europe.