Assange, 39, is currently on bail and living under house arrest in Britain as he fights extradition to Sweden on alleged sex offences.
The Guardian reports he has sold the publishing rights to his memoir to Canongate in Britain and Knopf in the U.S.
News of the memoirs leaked via a tweet from Spanish publisher Random House Mondadori. Canongate and Knopf are both part of the Random House stable. The publishing houses neither confirmed nor denied the report.
Assange, an Australian computer expert, has attracted the ire of the U.S. government after he published several hundred leaked diplomatic cables from U.S. embassies around the world on his site and in several news organizations it partnered with, including the Guardian, the New York Times, El Pais, Le Monde and Der Spiegel.
He is alternately hailed as an advocate for freedom of information and reviled as a troublemaker.
His former second-in-command Daniel Domscheit-Berg is set to tell the story of the WikiLeaks site in a book, Inside WikiLeaks: My Time at the World's Most Dangerous Website, to be released by German publisher Econ Verlag in January