Called Blackened Recordings, the label has taken over ownership of all the group's master recordings - including every current album and video - and will own all future releases.
The move comes as a result of a contract renegotiation made between Metallica and Warner Music Group in 1994, and marks the end of the pair's 28-year relationship.
"You may have heard us say it once or twice or a thousand times before, but it's always been about us taking control of all things," the band wrote on their website.
"Forming Blackened Recordings is the ultimate in independence, putting us in the driver's seat of our own creative destiny.
"We're looking forward to making more music and getting it all out to you in our own unique way."
Metallica release live DVD Quebec Magnetic, capturing the two 'World Magnetic Tour' shows in Quebec City in the autumn of 2009, on December 10.
Watch a trailer for the DVD below: