Saturday Night Live star Jost announced the news on Instagram on Wednesday (18 August), posting: “Ok ok we had a baby. His name is Cosmo. We love him very much.”
This is Johansson’s second child. She shares her six-year-old daughter, Rose, with ex-husband Romain Dauriac.
The surprise news comes in the same week that Jost first confirmed Johansson was pregnant during a stand-up comedy show. “We’re having a baby,” he had said. “It’s exciting.”
The Black Widow star married Jost in October 2020 after three years of dating.
The couple’s new arrival comes amid a row between Johansson and Disney over the release of her latest film Black Widow.
Johansson recently filed a lawsuit against Disney over its decision to part-stream the release of Black Widow alongside a cinema release.
The actor alleged that the online release violated her contract and that her compensation for the movie was “largely based” on Black Widow’s box office performance.
Disney hit back in a controversial statement, leaking Johansson’s $20m salary for the film and saying: “There is no merit whatsoever to this filing. The lawsuit is especially sad and distressing in its callous disregard for the horrific and prolonged global effects of the Covid-19 pandemic.”