"I am Chelsea Manning, I am a female," the statement read.
"Given the way that I feel and have felt since childhood, I want to begin hormone therapy as soon as possible," Manning said. "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)."
A former junior intelligence analyst serving in Iraq in 2010, Manning was found guilty of 20 charges including theft and espionage.
Manning leaked more than 700,000 classified files, including diplomatic cables, battlefield reports, and a video in which a U.S. helicopter guns down a Reuters journalist, photographer and civilians.
During the sentencing phase of Manning's court martial, the defense argued her struggle with gender identity was a factor in her decision to leak the files.
"It was never an excuse because that's not what drove his actions," explained Manning's lawyer, David Coombs. "What drove his actions was a strong moral compass."
"The stress that he was under was mostly to give context to what was going on at the time," Coombs said of the decision to bring it up during sentencing. The defense showed that supervisors were aware of Manning's struggle with being transgender before the leaks occurred.
Fort Leavenworth, the only military prison for sentences longer than ten years, does provide psychiatric care, but does not provide hormone therapy or sex-reassignment surgery, according to a spokesperson.
Coombs hopes Fort Leavenworth will "do the right thing" and provide hormone therapy for Manning, otherwise, he says, "I'm going to do everything in my power to make sure they are forced to do so."
Coombs also said he hasn't yet discussed the possibility of sexual reassignment surgery with Manning, but said Manning will be confined as a man.
In the U.S. prison system, transgender prisoners who have not had genital surgery are typically assigned to live according to their birth sex.
Manning will be credited with the 1,294 days he spent in pre-trial confinement plus an additional 112 days. She is required to serve one third of her sentence before becoming eligible for parole. Coombs expects Manning to be out on parole within nine years, if she isn't already pardoned by that time.
"I actually expect him to get pardoned," Coombs continued. "At least that's what my hope is, that the president will in fact pardon him."