The tech firm is working with the UN's World Food Programme (WFP).
It's difficult for large delivery trucks to access some parts of Ukraine because of structural damage and the threat of attack.
Uber's platform enables the WFP to co-ordinate a fleet of smaller vehicles.
The WFP is hand-picking its own drivers and vehicles, but some are former Uber drivers who worked in Ukraine before the Russian invasion.
Uber boss Dara Khosrowshahi said his firm had given the WFP "their own private-label Uber".
It's a bespoke version of the Uber Direct delivery platform which is available commercially - big name customers include Apple and Tesco. Usually, businesses pay Uber a commission per delivery for the service, but the WFP is not being charged.
It can use the software to co-ordinate distribution, and track deliveries and drivers within a 100km range of its warehouses.
The scheme is being trialled in the central city of Dnipro. The hope is that it will be rolled out later across four other cities: Lviv, Vinnytsia, Kyiv and Chernivtsi.