The company first revealed its plans to merge Messenger and Skype in November.
Microsoft has confirmed that its Windows Live Messenger service will shut down from 15 March 2013, and users will be migrated to internet communication platform Skype.
Microsoft said: "On 15th March 2013 we are retiring the existing Messenger service globally (except for mainland China where Messenger will continue to be available) and bringing the great features of Messenger and Skype together."
Users have been asked to update their Messenger to Skype and sign in using their Microsoft Messenger account, where all their IM contacts will be available.
"You'll be able to instant message and video chat with them just like before, and also discover new ways of staying in touch with Skype on your mobile and tablet," Microsoft said.
Microsoft acquired Skype for $8.5bn in August 2011 upon securing approval from the European Commission.
Skype has over 600 million accounts and is available for platforms that include Apple's Mac and iOS, Google's Android, and Windows.
Last year, Skype revealed plans to launch the new video-messaging feature that would allow its users to send short, pre-recorded messages to other Skype users.