The body says while progress has been made, it is not even
A new report from UNICEF says an estimated 69 million children under five will die by 2030, mostly from preventable causes.
In its annual flagship report, it says 167 million children will live in poverty, and 750 million women will have been married as children.
UNICEF says the report - 'The State of the World’s Children' - paints "a stark picture" of what is in store for the world's poorest children if governments, donors, businesses and international organisations do not accelerate efforts to address their needs.
"Inequality is the root cause behind this worrying statistic. Denying hundreds of millions of children a fair chance in life does more than threaten their futures - by fueling intergenerational cycles of disadvantage, it imperils the future of their societies," said UNICEF Ireland executive director Peter Power.
"We have a choice: Invest in these children now or allow our world to become still more unequal and divided."
The report notes that significant progress has been made in saving children's lives, getting children into school and lifting people out of poverty.
Global under-five mortality rates have been more than halved since 1990, boys and girls attend primary school in equal numbers in 129 countries, and the number of people living in extreme poverty worldwide is almost half what it was in the 1990s.
But it says this progress has been neither even nor fair.
The poorest children are twice as likely to die before their fifth birthday and to be chronically malnourished than the richest.
Across much of South Asia and sub-Saharan Africa, children born to mothers with no education are almost three-times more likely to die before they are five than those born to mothers with a secondary education.
And girls from the poorest households are twice as likely to marry as children than girls from the wealthiest households.
"Nowhere is the outlook grimmer than in sub-Saharan Africa, where at least 247 million children - or two in three - live in multidimensional poverty, deprived of what they need to survive and develop, and where nearly 60% of 20- to 24-year-olds from the poorest fifth of the population have had less than four years of schooling", it says.
UNICEF says at current trends, by 2030, sub-Saharan Africa will account for: