Finance Minister Christine Lagarde announced the aid after meeting her Ivorian counterpart Charles Koffi Diby in Ndjamena the day after forces loyal to elected President Alassane Ouattara arrested his rival Laurent Gbagbo.
"Lagarde announced that France would in the coming days, as soon as financial and security circuits are re-established, give one-off financial aid of 400 million euros," her ministry said in a statement.
The aid is "to finance emergency spending on the population, the city of Abidjan and restarting essential public services," the statement said after 10 days of fighting in the west African nation's commercial capital.
"It is also to help restart the economy and to allow Ivory Coast to make its overdue payments to international institutions," it added.