Former EU heavyweight Michel Barnier was named as the new French prime minister on Thursday by President Emmanuel Macron and vowed to cause "disruption" in a bid to bring the nation together.
Macron "has tasked him with forming a united government to serve the country and the French people," the Élysée Palace announced.
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The appointment of the conservative comes some two months after a snap parliamentary election called by centrist Macron resulted in a broad left-wing alliance coming out on top.
But no party or political alliance secured enough seats in the National Assembly, resulting in a hung parliament and weeks of political uncertainty.
It remains to be seen whether Barnier will be able to form a government coalition with a working majority. Macron had held days of talks with all sides in parliament to try to sound out the broadest and most stable government possible.
"This appointment comes after an unprecedented cycle of consultations during which, in accordance with his constitutional duty, the president ensured that the prime minister and the government to come would ... be as stable as possible and give themselves the chance to bring together as many people as possible," the Élysée added.
Oldest French prime minister on taking job
The 73-year-old Barnier, the oldest person to take up the role, has a political career spanning decades and is an influential figure in France's centre-right Republicans party.
He was French environment minister, foreign minister and agriculture minister between 1993 and 2009.
He has worked two stints as an EU commissioner. He also served as the European Union's chief Brexit negotiator.
French conservatives have emphasised that they do not want to be part of a coalition, but they are likely to at least tolerate a government led by Barnier.
There will be "changes and disruptions," he told reporters in Paris.
France is "in a serious situation" and a new chapter is about to begin. "We will act more than we talk," Barnier added.
He said he wanted to "respond to the challenges, the anger, the suffering, the sense of abandonment and injustice that pervade our cities, our neighbourhoods and our rural areas far too much."
What is needed is more listening and respect between the government and parliament, between the political parties themselves and with the public, the new premier added.
He is now set to have the support of the Macron camp in parliament but it is difficult to predict how and if he will get the necessary backing from the resurgent left.
It is possible that the far right will tolerate him - out of support for Barnier's restrictive positions on migration policy.
Macron forced to give up some power
France's system has a powerful president, akin to the US, but also a prime minister who runs business in parliament and tries to push through legislation.
Given the elections result, however, the liberal Macron will have to relinquish some authority. The prime minister will become more important as head of government policy, with Macron retaining the upper hand in foreign affairs.
Macron called July's elections after a disappointing showing from his camp in the EU parliamentary poll in June.
The left-wing alliance New Popular Front came out ahead of Macron's centrist forces and the far-right National Rally led by Marine Le Pen, which had been in front after the first round of voting.
None of the groupings received an absolute majority and the process of forming a French government has therefore stalled. Previous prime minister Gabriel Attal, the youngest ever at 34, led a caretaker government until now.
Macron said in a statement: "Thank you dear Gabriel Attal for these eight months as prime minister.
"Through the government, you have moved the country forward and contributed to its influence at an important time - at the service of our fellow citizens, with France at your heart."
The main challenge for Macron was to find a new prime minister who did not have a majority against him and could avoid being toppled.
