The global health group has previously advised a lower sugar intake, but stopped short of backing tax measures.
Several countries, including Mexico and Hungary, already tax added sugar products.
South Africa is introducing a sugar tax . It's the only country in Africa to do so.
The WHO said it wants to see lower consumption of "free sugars", which it said will lower incidences of obesity, diabetes and tooth decay.
"Free sugars" are all the different types of sugar in the diet, except for the sugars that are found naturally in fruit and milk.