The report states there is "strong evidence" that a sugar tax will work alongside two other measures to tackle child obesity - a crackdown on the marketing of junk food to children and schools to ban the sale of unhealthy food.
WHO stated at least 41 million children under the age of five are obese or overweight across the globe, which prompted these measures.
WHO's Commission on Ending Childhood Obesity said, according to PA: "The Commission believes there is sufficient rationale to warrant the introduction of an effective tax on sugar-sweetened beverages.
"It is well established that the consumption of sugar-sweetened beverages is associated with an increased risk of obesity."
Prime Minister David Cameron has previously said he does not see the need for a sugar tax, while supporters such as Jamie Oliver have urged him to reconsider.
However the numbers of obese or overweight children has risen by 10 million worldwide since 1990, which has caused WHO to call for tight regulations.
In the report, it stated: "Processed, energy-dense, nutrient-poor foods and sugar-sweetened beverages, in increasing portion size, at affordable prices have replaced minimally-processed fresh foods and water in many settings at school and family meals.
"The easy access to energy-dense foods and sugar-sweetened beverages and the tacit encouragement to 'size-up' through commercial promotions have contributed to the rising caloric intake in many populations."
Members of the WHO Commission called for tighter regulations around the advertising of food and drinks to children.
The report stated, according to PA: "Despite the increasing number of voluntary efforts by industry, exposure to the marketing of unhealthy foods remains a major issue demanding change that will protect all children equally.
"Any attempt to tackle childhood obesity should, therefore, include a reduction in exposure of children to, and the power of, marketing."
The report also stated schools should ban the "provision or sale of unhealthy foods, such as sugar-sweetened beverages and energy-dense, nutrient-poor foods, in the school environment".
It stated: "Childhood obesity is reaching alarming proportions in many countries and poses an urgent and serious challenge.
"Children with obesity are very likely to remain obese as adults and are at risk of chronic illness.
"Progress in tackling childhood obesity has been slow and inconsistent."