Users of Bebo will be able to see the status of other users of Windows Live Messenger and click through to the instant messenger service to get in touch.
Bebo has risen in popularity since its launch only two years ago, to become the most used social network in the UK with 10.6 million registered UK users.
The tie-up with Microsoft is the first of its kind, other than the integrated offering Microsoft provides within its own social network, Windows Live Spaces.