London-based Pulse Films made the announcement at the opening of the Cannes film festival, on the day of Manning's planned release from a maximum-security military prison.
The film, XY Chelsea, by director Tim Travers Hawkins and co-produced by Oscar winner Laura Poitras, will start filming with Manning later Wednesday "as she walks free and begins to tell her story", Pulse said in a statement.
"Chelsea Manning's story is one of the major events of our time, covering a wide range of themes from transgender rights to surveillance to the very nature of core democratic principles," Pulse's head of documentary films Julia Nottingham said.
In July 2010, Manning -- then a male soldier known as Bradley -- was arrested over the release of a huge trove of more than 700,000 classified military and diplomatic documents via WikiLeaks.
On Wednesday, Manning will leave the prison barracks at Fort Leavenworth in Kansas thanks to a commutation of her sentence by president Barack Obama before he left office.
Manning, who served as an intelligence official in Iraq, would otherwise have remained behind bars until 2045, after serving a 35-year sentence.
"It was by far the longest sentence given to any whistleblower in US history," Pulse said, saying the film would depict "the journey of her fight for survival and dignity, and her transition from prisoner to a free woman."
The film's team will present footage to potential buyers at the Cannes film festival, which runs until May 28.
To read our coverage of the Cannes film festival 2017, click here.