The move will enable film fans to watch the forthcoming sci-fi epic Dune and the Matrix sequel on HBO Max at the same time as their cinema release.
Typically, new releases are shown exclusively at cinemas for months.
But with many cinemas shut due to the virus, studio revenues have plunged.
As a result, Warner Bros said all of its 2021 releases would go straight to HBO Max, the streaming service owned by its ultimate parent company AT&T.
The films will be available on the service, which is not yet available in the UK, for one month after release.