The International Alliance for Responsible Drinking (IARD), which includes Anheuser-Busch InBev, Diageo and Pernod Ricard, say age-restriction symbols or wording would be in place in all markets by 2024.
The labels would also extend to alcohol-free versions of established brands.
The IARD, which has previously run educational initiatives, said underage drinking was declining in many countries but the trend was not universal
The producers have agreed that online safeguards would go beyond the more usual current practice of asking website visitors to confirm they are a given age.
They said partnerships with Facebook, Snapchat and YouTube were helping to remove children who might misreport their ages. Their real ages could be exposed, for example, by interests that were more common for children or by their choice of friends.
IARD said it was also looking into extending the ability of adults to opt out of alcohol marketing.
Producers have agreed to apply tighter safeguards for at least 95% of online alcohol marketing by 2024.
Asahi, Bacardi, Beam Suntory, Brown-Forman, Carlsberg, Heineken, Kirin, Molson Coors and William Grant & Sons are the other signatories.
(Reporting by Philip Blenkinsop; Editing by Kirsten Donovan)
