Updated overnight, the Facebook Messenger app now includes a new 'Record' option when hitting the '+' button next to the message box.
Activating this enables the user to record an up to one-minute-long voice message and then send it to their contacts.
The message appears in the conversation stream in an audio wave form that can be listened to.
Voicemail is fairly old technology, but the service still has its uses, such as when messages need to be sent hands-free while driving, or times when lengthy instructions are more easily explained vocally than typed.
The service could also be used for sending short clips of other audio, such as snippets of music, as part of a wider conversation.
Its addition is part of Facebook's attempts to expand its own Messenger application and pull users away from rival services, such as the hugely popular WhatsApp.
According to TechCrunch, Facebook is separately testing an open source voice-over IP (VoIP) calling service between iOS Messenger users in Canada running over mobile data plans.
It is unclear whether the free web calling service will expand to other countries, or how it will impact on Facebook's existing partnership with Microsoft's Skype, but it is thought to be part of the social network's efforts to gain greater control over social communications.