Napster was launched in 1999 as a peer-to-peer file-sharing service that popularized online music sharing.
But Napster was found to be facilitating music piracy and shut down by US courts in 2001, leading to bankruptcy.
The brand was acquired by Best Buy in 2008 for $121 million, before being sold to Rhapsody.
A blog post Tuesday on Rhapsody said little about the change, with a headline, "Rhapsody is becoming Napster."
"No changes to your playlists, favorites, albums, and artists. Same music. Same service. Same price. 100% the music you love. Stay tuned!," Rhapsody said.
With an estimated 3.5 million subscribers, Rhapsody has been trailing other online music services such as Spotify, Pandora and Apple Music.