It's after the resignation of Edouard Philippe who has been in the post for three years.
Mr Castex, 55, is relatively unknown in France, although he is a senior civil servant.
The new Prime Minister has been a key player in the government's response to the Covid-19 pandemic.
Trump says US and Tehran having 'good talks'
President Donald Trump said on Monday that the US was having "good talks" with Iran and there was a chance of a deal over their conflict, but warned US strikes would resume if the negotiations failed to deliver.
Israel to allow international force into Gaza, Israeli official says
Israel will allow a multinational security force to enter Gaza as proposed under US President Donald Trump's ceasefire plan for the enclave, an Israeli official said on Sunday, a day before Prime Minister Benjamin Netanyahu heads to Washington.
Saudi Arabia reaffirms right to defend its security against drone attacks
Saudi Arabia's air defences intercepted and destroyed drones launched from Iraq on Monday and reaffirmed its right to respond to the sources of "the aggression".
UK's Burnham welcomes Zelenskyy as first foreign visitor
Britain's new prime minister, Andy Burnham, welcomed Ukrainian President Volodymyr Zelenskyy as his first international visitor on Monday, in a move that underscores London's steadfast support for Ukraine.
Philippines' Marcos puts anti-graft campaign at centre of address to Congress
Philippine President Ferdinand Marcos Jr. on Monday vowed to press ahead with an anti-corruption drive that could see multiple charges filed against his cousin, former House Speaker Martin Romualdez.
As many as 42 domestic worker recruitment offices in the UAE have been penalised for breaking employment rules during the first half of 2026.
Dubai's Roads and Transport Authority (RTA) has expanded e-bike delivery service to seven new areas, including Dubai Media City, Jumeirah Lakes Towers and Dubai Marina, to boost connectivity.
Sharjah Charity International (SCI) has provided food aid to those affected by the floods in Bangladesh, as part of its humanitarian efforts to alleviate the impact of the natural disaster on families.
