"I am Chelsea Manning. I am female," the Army private wrote in a statement read on NBC's "Today" Thursday by his attorney. "Given the way that I feel, and have felt since childhood, I want to begin hormone therapy as soon as possible. I hope that you will support me in this transition."
Manning was sentenced to 35 years in military prison Wednesday.
He was previously found guilty of 20 charges, including espionage and theft, for leaking more than 700,000 documents to WikiLeaks.
"I also request that, starting today, you refer to me by my new name and use the feminine pronoun [except in official mail to the confinement facility]," he continued in the statement. "I look forward to receiving letters from supporters and having the opportunity to write back."
During the trial, Manning's attorneys discussed Manning's struggles with gender identity as a gay soldier and cited those difficulties as a factor in Manning's decision to leak the documents.