The band split in 1997, but former frontman Cornell recently gave hope to fans by admitting he would "never count out" the idea of a reunion.
Now the singer has confirmed the rockers, including guitarist Kim Thayil, bassist Ben Shepherd and drummer Matt Cameron, are back together and planning a series of concerts.
In a post on his Twitter page, Cornell writes, "The 12 year break is over and school is back in session. Knights of the Soundtable ride again!"
All four members attended a Pearl Jam show in Los Angeles in October when Cornell briefly reunited grunge supergroup Temple Of The Dog, and plans for a Soundgarden reunion are said to have taken shape shortly afterwards.
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