About 1,800 children did develop thyroid cancer, a treatable disease which is rarely fatal, and more cases are expected, an IAEA statement said on Tuesday.
"However, with this exception, there is no scientific evidence of increases in overall cancer incidence or mortality or in non-malignant disorders that could be related to radiation exposure," it said.
Thirty-one people died from radiation poisoning in the explosion and its immediate aftermath.
Radiation exposure
Health experts feared that thousands living nearby would develop cancers as a result of the high levels of radiation emitted.
But a report by the UN's committee on the effects of atomic radiation (Unscear) "concludes that there is no evidence of a major public health impact attributable to radiation exposure 14 years after the accident," the Vienna-based IAEA said.
It is thought the thyroid cancers were caused by radioactive iodine - one of the most serious sources of radiation in the fallout.
Iodine, which is found in certain foods and milk, collects in the thyroid gland.
The children, who drank more milk and had smaller thyroid glands, received a radioactive dose about three times higher than adults.
Disputed figures
The precise impact of the Chernobyl disaster has always been disputed. According to a group representing those who worked in the relief operations following the explosion about 15,000 people were killed.
Ukraine's own health ministry has estimated that 3.5 million people, over a third of them children, have suffered some illness as a result of the contamination.
Levels of radioactivity remain unexpectedly high in some parts of northern Europe, according to one recent report.
It said restrictions on some foods would have to remain in place for up to 50 years.
The nuclear power plant, after further minor leaks and safety worries, is due to close at the end of the year.