Mr Villepin, the former Interior Minister, earned his international reputation for his defence of France’s opposition to the war in Iraq.
Mr Villepin, 51, is expected to bring a fresh impetus to government policy, after Mr Chirac promised voters that change would be afoot.
His appointment comes after Monday meetings between the president and Mr Raffarin, and the president and political heavyweights, fanning widespread speculation that a change in leadership was imminent.
Other likely contenders Mr Chirac met with were Defence Minister Michele Alliot-Marie and ruling UMP party leader Nicolas Sarkozy.
Mr Chirac is expected to order major policy changes, in an effort to control the damage after his crushing defeat in Sunday’s referendum.
He is due to address the nation later on Tuesday.
Mr Raffarin’s unpopular economic reforms and poor record on jobs are blamed in part for Sunday’s result.
French voters overwhelming rejected the EU constitution, dealing a severe blow to Europe’s ambitions of political union and to Mr Chirac’s leadership.
According to a new poll, 48 percent of French voters believe early elections should now be called.
The no vote saw France, one of the EU’s six founding members, become the first country to turn down the landmark charter.
The result also means Paris now risks losing its pre-eminent position inside the expanded 25-member bloc.
“This is the first time in 50 years that the French and Germans have diverged in Europe on a fundamental issue. Without this constitution, Europe is broken down politically,” said Foreign Minister Michel Barnier.
The rejection by French voters leaves the future of the constitution, which needs to be ratified by all 25 member states, unclear.
“There is a very serious problem and we can’t really say it’s ‘business as usual’,” said European Commission chief Jose Manuel Barroso.
The constitution’s next test comes on Wednesday, with a referendum in the Netherlands.
Analysts say France’s rejection of the treaty could lend weight to the ‘no’ vote there, and opinion polls already show the ‘no’ camp in the lead.
A Dutch rejection would make it harder for EU leaders to call repeat votes in countries that oppose the charter and could deal it a fatal blow.
Britain takes over the EU’s rotating presidency on July 1.
After lengthy negotiations, the constitution was drawn up last year with the aim of streamlining EU institutions following the admission of 10 new members.