According to XDA Developers, the feature allows users to watch TV shows and movies together over the internet.
Amazon hasn't made any announcements regarding the rollout.
Compatible devices for Watch Party playback include desktop browsers (except Apple Safari and Internet Explorer) and on FireTV devices, exclusively in the Prime Video app, according to the Watch Party FAQ section.
"In order to host or join a Watch Party on a FireTV device, you first must open the Prime Video app," it added.
According to the statement, playback is not supported on mobile devices, but the latest version of the Prime Video app on the mobile device supports Watch Party chat and makes it easier to share a link to your Watch Party with family and friends.
Fire TV devices now offer the complete Watch Party experience, while the Amazon Prime Video app for mobile offers chat-only support, the report said.
This means that Prime Video subscribers will be able to watch TV shows and movies with their friends on supported Fire TVs and chat with them in real-time on mobile devices, it added.