India (22 per cent) and Nigeria (13 per cent) together account for more than one-third of all deaths of children under the age of five, the report said.
The report by UNICEF, WHO, the World Bank Group and the United Nations Department of Economic and Social Affairs/Population Division, also found that global child deaths decreased by almost half since 1990.
In 2012, approximately 6.6 million children worldwide -- 18,000 children per day -- died before reaching their fifth birthday.
This is roughly half the number of under-fives who died in 1990, when more than 12 million children died, the report said.
"This trend is a positive one. Millions of lives have been saved. And we can do still better," said AnthonyLake, UNICEF executive director.
"Most of these deaths can be prevented, using simple steps that many countries have already put in place -- what we need is a greater sense of urgency," said Lake.
The leading causes of death among children aged less than five years include pneumonia, prematurity, birth asphyxia, diarrhoea and malaria. Globally, about 45 per cent of under-five deaths are linked to undernutrition.
About half of under-five deaths occur in only five countries: China, Democratic Republic of the Congo, India, Nigeria, and Pakistan, according to the report.
"Care for mother and baby in the first 24 hours of any child’s life is critical for the health and wellbeing of both," said Dr Margaret Chan, Director-General at WHO.
"Up to half of all newborn deaths occur within the first day," said Chan.
The report said that lives of most of these babies could be saved if they had access to some basic health-care services.
These include skilled care during and after childbirth; inexpensive medicines such as antibiotics; and practises such as skin-to-skin contact between mothers and their newborn babies and exclusive breastfeeding for the first six months of life.
While the global average annual rate of reduction in under-five mortality accelerated from 1.2 per cent a year for the period 1990–1995 to 3.9 per cent for 2005–2012, it remains insufficient to reach Millennium Development Goal 4 which aims to reduce the under-five mortality rate by two-thirds between 1990 and 2015, the report said.
Sub-Saharan Africa, in particular, faces significant challenges as the region with the highest child mortality rates in the world.
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