Maurice Robinson, 25, was arrested after the bodies of 31 men and eight women were found in Grays on Wednesday.
He is further charged with people trafficking, immigration and money laundering offences, Essex Police said.
Mr Robinson, of Laurel Drive, Craigavon, Northern Ireland, is due before Chelmsford Magistrates' Court on Monday.
Three others, a man and a woman, both 38, from Warrington, Cheshire, and a 48-year-old man from Northern Ireland remain in police custody.
All three were arrested on suspicion of manslaughter and conspiracy to traffic people.
