The app will rely on Bluetooth to determine distances between phone users and encryption to ensure data security, the two companies said.
"Privacy, transparency and consent are of utmost importance in this effort," the companies said in a statement published on Google's blog site.
In a first step, a programming interface (API) will be released in May, which will enable collaboration between Android and iOS devices using apps from health authorities.
These official apps would be available for users to download through their respective app stores.
In a second step, the two companies will work "in the coming months" to enable a more comprehensive, Bluetooth-based platform for tracking contacts, they said.
The concept envisages smartphones constantly exchanging temporary identification numbers, regardless of the phone's operating system, so that the users' privacy is preserved in the process.
The system proposed by Apple and Google would save the temporary IDs and contact details of others only on the smartphones themselves, not on a central server.
Only when someone tests positive for coronavirus will the information be transferred to a central server - and only if the patient concerned agrees.
The other smartphones then call up a list of the anonymised IDs of the person's contacts to see whether they themselves have had contact with an infected person.
Google and Apple want to ensure, among other things, that this constant exchange of IDs does not significantly reduce device battery life.
© DPA 2020