“The current health situation has required that we create a new WWDC 2020 format,” Apple said in a statement.
The June conference is often used to announce new products and software features.
Only open to Apple software developers, the $1,600 (£1,280) tickets sell out every year.
Apple said it “will host its annual Worldwide Developers Conference in June…[in] an entirely new online format”.
Full details will follow in the coming weeks, but Phil Schiller, the company’s marketing chief, promised “a full programme with an online keynote and sessions”.
The company will also put $1m (£800,000) towards local organisations in San Jose, California, “to offset associated revenue loss as a result of WWDC 2020’s new online format”.
The annual keynote speech from CEO Tim Cook is usually streamed online each year anyway, to a much larger audience than the one in the convention centre in San Jose.
There had been widespread speculation about the fate of the conference as the world battles to contain the spread of the coronavirus. Avoiding large gatherings is a key part of much public health advice.
Attendees in previous years have come from all over the globe. Apple says its developer programme includes 23 million people in 155 countries.
Last year’s conference saw two major hardware announcements: a new Mac Pro, and the high-end Pro Display XDR monitor. The event also showcases new features coming to Apple’s software, such as iOS and macOS.
Apple’s physical gathering of thousands is the latest such technology event to be called off because of the coronavirus.
Earlier, the gaming industry’s flagship event E3 was called off entirely, with a note that organisers were “exploring options” for an “online experience” in June.
The Ted conference of talks was also postponed, and organisers considered an online event as a replacement before opting for a later date.
The Game Developers Conference, SXSW, Mobile World Congress, and Google and Facebook’s major conferences have also been hit.
In the UK, public health advice is to self-isolate at home for a week if you develop a new, persistent cough, or a fever. English local elections have been postponed, and many major sports events cancelled.