The Verge cites "several sources" as saying that Messenger will be retired in the "coming months" and its functionality integrated into Skype, the internet telephony firm that Microsoft acquired last year for $8.5 billion (£5.3 billion).
It is understood that Microsoft has been migrating users over to the Skpe back-end over the past few months. The Verge claims that around 80% of instant messages now sent on Skype are being run through Messenger.
The site's sources say that Microsoft will announce the end of Windows Live Messenger "soon".
In preparation, the firm has already been linking Skype accounts to Microsoft ones. Users of Skype 6.0 for Mac and Windows now get the option to log in using a Microsoft or a Facebook account.
Microsoft has not commented on the report.
> Skype launches prepaid credit cards in the UK
> Microsoft takes on Google, Apple with Windows Phone 8