The company announced the move Thursday during a presentation to debut new features in New York.
Metallica had previously declined to stream its music. Fans can now access 30 years of the Rock and Roll Hall of Fame band's recordings.
The move is significant for the band.
Metallica was among several acts who sued Napster in 2000, eventually forcing a settlement that required Napster to evolve into a pay-for-use service that became something of a model for today's streaming companies.
Drummer Lars Ulrich says in a news release the band has waited a long time to see how the music streaming service model would evolve and is "beyond psyched to unleash our music through" Spotify.
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