Funded by the New Zealand government, the agreement targets the first 1000 days - from pregnancy to age two.
Kiribati has the highest infant mortality rate in the Pacific, with one in 25 children dying before the age of one.
UNICEF's Pacific Representative Sheldon Yett said contributing to the rate were preventable diseases like diarrhoea.
"Water, sanitation and hygiene are issues throughout the country. Pneumonia and pneumonia related diseases too are a problem in Kiribati as well as sepsis, preeclamapsia and other complications related to child birth."
Mr Yett said some of the funding would be used to promote greater use of primary health care centres, which are often overlooked by i-Kiribati.
"The tendency (is) for people to not have confidence in the local services and wanting to skip to the top, wanting to go to tertiary services, the high-end hospitals, and that's a problem. Children die unnecessarily because of that.
"There are some 102 primary health care centres throughout the country and there is a tendency for people not to use them and to wait until symptoms get really bad and to go to one of the four major hospitals. That's a mistake."
Money would also be devoted to improving primary health care services, to give people confidence to access local nurses and doctors, Mr Yett said.
"To provide the best kinds of care and to ensure that service providers know what the standards of care are. Ensuring that they have the supplies and ensuring supportive supervision is in place... Good management of the services, good outreach. Good work in the communities themselves so that people understand what's available and how to hold local authorities accountable for providing those services."