The site has been in exploratory talks with agencies for almost a year, as PRWeek reported last May.
It is now understood to have appointed House PR, following a lengthy pitch process.
The appointment comes as MySpace, once a pre-eminent force in social networking, battles to redefine itself as an online music provider.
Referring to the recent announcement on Twitter that its updated offering will be music-focused, an agency source said: ‘It will be a crowded marketplace, with many social networks exploring a presence in music, so MySpace will have to be aware of that. One challenge will be getting people to reappraise MySpace, while also introducing it to new consumers.’
However, it has struggled against competition from Pandora and Spotify, and late last year was reported to be seeking $50m (£32.7m) to relaunch.
MySpace had not responded to requests for comment as PRWeek went to press, while House PR declined to comment.