Appointment reminders, invitations to health screenings and test results will now be received by patients on their phones.
The government says moving to a more digital-focused NHS will mean 50 million fewer letters need to be sent out by the health service, saving an estimated 拢200m over the next three years.
Instead, under the new plans, millions of people will be notified about appointments and other important notices via the NHS app on their phone or digital device.
The app is set to become the go-to method for the NHS to communicate with people, the Department of Health and Social Care said.
The changes will be backed by more than 拢50m investment. It will see a predicted 270 million messages sent through the app this year, an increase of around 70 million on the last financial year, the government announced.
Wes Streeting has said this is all about modernising, as the NHS "feels so 20th century".