Joe Exotic Files for Divorce from Husband Dillon Passage

Joe Exotic is giving up on his marriage while he sits behind bars ... because he just filed for divorce.

The 'Tiger King' star filed divorce docs Thursday after more than 4 years of marriage to Dillon Passage ... and in the docs, obtained by TMZ, Joe says the marriage is irretrievably broken.

Joe and Dillon have been estranged for about a year ... as we first told you, Dillon called Joe in prison last March and told Exotic he wanted out of the relationship and divorce was on the table.

But, Joe is the one actually pulling the trigger on the divorce ... his legal team says Dillon never followed through on his divorce threat.

TMZ broke the story ... Dillon's already moved on with a new boyfriend, and Joe is looking for love too.

Joe and Dillon tied the knot on Dec. 11, 2017 ... 2 months after Joe's previous husband, Travis Maldonado, died after accidentally shooting himself.

In the docs, Joe says he's in need of alimony in the form of a lump sum and says he wants to change his name from Joseph Allen Maldonado-Passage back to Joseph Allen Maldonado.