HBO is cutting the cord, threatening the traditional cable-TV bundle of channels by offering its popular service directly to viewers over the Internet.

Time Warner Inc. on Wednesday said HBO would launch the stand-alone, online streaming version of its service next year.

It will primarily target the 10 million people in the U.S. who have an Internet connection but no pay-television service, said Richard Plepler, chairman and chief executive of HBO, during a Time Warner investor presentation in New York.

“That is a large and growing opportunity that should no longer be left untapped,” Mr. Plepler said. “It is time to remove all barriers to those who want HBO.”

Consumers have been pushing for HBO to free itself from having its premium service packaged with large bundles of channels, many of which are never watched by subscribers.