The phone is the firm’s first sliding keyboard model, and also features a track-pad and touch-screen.
The firm hailed the device as the “best BlackBerry ever”, calling the release one of the most important in its history. As well as the new hardware, the phone offers an updated version of the BlackBerry software which allows better web browsing and more intuitive access to its app store.
It was released in the US in an exclusive deal with mobile operator AT&T and will cost $199 (£125) with a $15 or $25 a month contract.
Release dates for the UK and Europe, as well as further pricing information, is expected soon.
BlackBerry, which was hit last week by a ban on its email and Messenger services in the UAE after refusing to unencrypt user data, is hoping the phone will compete with big-name rivals including the iPhone and models powered by Google’s Android software.