In a written statement provided to NBC's "Today" show on Thursday morning, Manning said he will begin hormone therapy and live as a woman named Chelsea.
A military judge announced Manning's sentence on Wednesday. Manning's struggle with gender identity disorder - his sense that he was a man trapped in a woman's body - was a key part of his defense.
Attorneys had presented evidence of Manning's struggle with gender identity, including a photo of the soldier in a blond wig and lipstick that he sent to a therapist.
It's unclear how Manning will get hormone therapy at Fort Leavenworth, because the military doesn't allow that type of treatment or transgender individuals in the military.
A Pentagon spokesperson told ABC News on Thursday that military ruled do not allow for transgender individuals to serve in the military, so hormone therapy and sexual reassignment surgery aren't possible.
On "Today," Manning's attorney David Coombs said he hopes that Fort Leavenworth "would do the right thing and provide" the hormone treatments. If not, Combs said he would do everything in his power to force them to provide the treatments.
The Associated Press and ABC News contributed to this report.