LOS ANGELES—Walt Disney Co. ’s superhero epic “Avengers: Endgame” became the first movie to gross more than $1 billion in its debut at the world-wide box office.

The Marvel Studios blockbuster, powered by record-setting hauls in the U.S. and China, collected an estimated $1.2 billion in its first five days of release. An estimated $350 million of that total came from the U.S. and Canada, an amount that blew past the previous opening-weekend record set last year by “Avengers: Infinity War” by about $92 million.

Hollywood had expected “Endgame” to set a record, but the movie’s performance stretched the limit of what many studio executives thought was even possible in an opening weekend. Demand forced exhibitors to dedicate about half the nation’s screens to the superhero movie, with dozens of locations screening it round-the-clock and even 2 a.m. showtimes selling out.

Over the past 11 years, Marvel’s superheroes have reigned at the box office, a result of a strategy set by the studio in 2008 with the release of “Iron Man.” Interconnected story lines and characters—from Thor to Doctor Strange to Captain Marvel—have helped place Disney on an unprecedented winning streak at the box office. In just over a decade, Marvel’s success has prompted rival studios to hunt for their own franchises, provided a much-needed boon to a struggling exhibition industry and turned comic-book superheroes into one of America’s most popular exports.

“Endgame” could become the highest-grossing movie of all time, beating the record set by “Avatar,” which made $2.79 billion globally in 2009. After just five days of release, it is already No. 18 on the world-wide box-office chart.