The project will see capacity of the Leavesden facility near London growing by more than 50%.
It will create 4,000 "direct or indirect" jobs across the country, according to the media giant.
Warner Bros also says the expanded studios will become a primary production hub for DC Studios, the home of Superman, Batman and Wonder Woman.
The company also said the expansion would increase the value of its production in the UK by £200m a year, bringing it to £600m.
The announcement was made during a visit to Los Angeles by Chancellor Jeremy Hunt.
"Warner Bros Discovery's ambitious plan to grow its Leavesden studio is a huge vote of confidence in the UK," he said.
Mr Hunt added that it means "British-made entertainment will continue to delight and entertain global audiences".
Building work on the expansion of the studios, where Harry Potter and House of the Dragon were also filmed, is due to start by the summer of 2024.
It is expected to be completed in 2027, boosting the number of stages at the facility from 19 to 29.
About 10% of the land for the development is in Watford borough with the rest in the Three Rivers district.
Warner Bros said in its statement that "the expansion plan has been developed in close consultation" with the two councils "with careful consideration given to prioritising sustainability".
The investment comes as Warner Bros Discovery's productions in California have been hit hard by the first joint writers' and actors' strikes in more than six decades.
The walkouts have delayed major projects and prompted the company to cuts its revenue forecasts for the rest of the year.
PASTED FROM THE BBC