Manning's attorneys said she is scheduled to leave prison on May 17, though details haven't been released.
Manning, who is transgender, was convicted in 2013 of leaking classified information about USA national security activities that were later disclosed by WikiLeaks.
"Freedom was only a dream, and hard to imagine. Now, freedom is something that I will again experience with friends and loved ones after almost seven years of bars and cement, of periods of solitary confinement, and of my healthcare and autonomy restricted, including through routinely forced haircuts", she said.
Former President Barack Obama commuted all but four months of Manning's remaining sentence just before he left office in January.
Chelsea Manning, the Army intelligence analyst convicted of leaking classified information to anti-secrecy website Wikileaks, will be released from prison this week.
Manning, who was sentenced by a court-martial to a 35-year prison term for espionage and theft in 2013, had her sentence commuted in January by outgoing president Barack Obama.
Chelsea Manning thanks supporters before release from prison
The US army charged Manning with 22 counts relating to the unauthorised possession and distribution of more than 700,000 secret diplomatic and military documents and videos. She also said she released information that she didn't believe would harm the U.S. "I can imagine surviving and living as the person who I am and can finally be in the outside world", Manning wrote.
On Tuesday, she thanked her supporters, as well as President Obama for giving her the opportunity to be free.
The former Army private tried committing suicide twice during her imprisonment, spending time in solitary confinement as punishment.
The American Civil Liberties Union filed friend-of-the-court briefs in support of the appeal of Manning's conviction and represents her in a lawsuit against the Department of Defense that was first filed in 2014 over the department's refusal to treat her well-documented gender dysphoria.
Manning twice attempted suicide past year at the male military prison where she is being held at Fort Leavenworth, Kansas.
"I am forever grateful to the people who kept me alive, President Obama, my legal team, and countless supporters", said Manning on Tuesday, citing struggles over "nearly seven years of bars and cement, of periods of solitary confinement, and of my health care and autonomy restricted, including through routinely forced haircuts". "It has been far too long, too severe, too draconian", Manning's attorneys, Nancy Hollander and Vincent Ward, said in a joint statement.
She also went on a hunger strike previous year, which she ended after the military agreed to provide her with gender transition treatment.
Stroman, Goins help Jays post 4-2 win over Indians
Jason Kipnis is hitting.333 (3-for-9) with one homer and two RBIs against him. "They outplayed us today, so they deserved to win". According to the Swedish website Expressen , Leafs prospect Pierre Engvall has signed a two-year deal with HV-71 of the SHL.