Officials at Fort Leavenworth say Bradley Manning has arrived at the U.S. Disciplinary Barracks to begin serving his 35-year prison term.
Manning had previously spent nearly two years at an adjacent prison while awaiting court-martial.
The soldier was sentenced Wednesday for sending classified government material to WikiLeaks.
Manning announced Thursday that he intends to live as a woman and go by the name Chelsea Manning. Manning asked the Army to begin hormone therapy as soon as possible.
Army spokesman George Marcec says Manning will have access to mental health professionals, but the prison system does not provide hormone therapy or gender reassignment surgery for inmates.