It will see full-colour, graphical Yahoo! Messenger pre-installed on BlackBerry devices over coming months, which will allow users to send and receive instant messages, participate in online conferences, and tell which contacts are online.
It adds to the Yahoo! services already available on BlackBerry, including news and mobile internet.
Doug Garland, senior vice-president of Yahoo! Mobile, said: "Yahoo! has become an essential part of the lives of millions of its users and by bringing the services they love to these great mobile devices we are making it easier for people to communicate however they want, anywhere, anytime."
BlackBerry already allows users to keep in contact via email, text message and over the phone, while on the move. It also lets people tap in to corporate databases, go on the internet and acts as a personal organiser.
The new Yahoo! Messenger service is made possible by technology from Research In Motion, which makes hardware and software for the mobile communications market.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .