Capacity will be limited and restricted to residents of California, and venues will operate under new "guiding principles" designed to guard against the spread of Covid-19.
These include enhanced cleaning procedures, strict social distancing, and reduced contact.
Attendance will be by reservation only, with guests aged two and up will be required to wear face coverings, as will all cast members and employees.
Temperature checks will also be required for entry to some locations.
Disney has stressed that people’s experience may differ somewhat from what they are used to, adding certain attractions, experiences and services would either be limited or closed.
Magic Morning and Extra Magic hours are suspended, while parades and night-time spectaculars will return at a later date. Character meet-and-greets will also not take place initially.
The phased reopening in California will see Disney’s Grand Californian Hotel and Spa reopen on 29 April, followed by the two theme parks on 30 April.
Downtown Disney District is already open, with Disneyland Hotel and Disney’s Paradise Pier Hotel due to reopen at a yet unspecified later date.
"The day all of us have long been waiting for is almost here,” said Ken Potrock, president of the Disneyland Resort. “We’re excited to have more than 10,000 cast members returning to work as we get ready to welcome our guests back to this happy place."
Disney added: "While it may be a bit different from the last time you visited, together we can find new ways to create magical moments together—and memories to treasure for ever."