Maude Ballou, King's close friend and personal secretary, had possession of the documents before they were sold Thursday.
The artifacts included King's handwritten outline of his 1960 Dexter Avenue Church Farewell Address, which sold for $31,350.
Two letters that King wrote to Ballou from India while he was studying Gandhi's philosophy of non-violence sold for $18,750 and $17,500.
Two autographed chapters from his first book, "Stride Toward Freedom," sold for $8,125.
"This was simply an unprecedented auction of amazing, evocative material that provides a ground-level perspective of the civil rights struggle," Sandra Palomino, director of historical manuscripts at Heritage Auctions, said. "There was worldwide interest in the material and the emotional response to it was huge."