Baldwin, 64, has repeatedly said he was told by the crew that the gun was not loaded.
The former "30 Rock" star has also previously insisted he did not pull the trigger, though FBI firearms experts have said this is not possible.
Baldwin's attorney Luke Nikas vowed to beat the charge, which he called a "terrible miscarriage of justice."
"Mr Baldwin had no reason to believe there was a live bullet in the gun -- or anywhere on the movie set," he said.
"He relied on the professionals with whom he worked, who assured him the gun did not have live rounds. We will fight these charges, and we will win."
Lawyers for Gutierrez-Reed said they were confident the young armorer would be cleared.
"Hannah is, and has always been, very emotional and sad about this tragic accident. But she did not commit involuntary manslaughter," said a statement issued by attorneys Jason Bowles and Todd Bullion.
"These charges are the result of a very flawed investigation, and an inaccurate understanding of the full facts."
Live rounds on set
Assistant director Dave Halls, who handed Baldwin the weapon and told him it was "cold" -- industry speak for safe -- has agreed to plead guilty to negligent use of a deadly weapon.
He will serve a suspended sentence and six months of probation, a statement said.
Baldwin, a co-producer of the movie, and Gutierrez-Reed have been charged with two alternative counts of manslaughter involving different levels of negligence.
Both counts entail a maximum 18-month jail term, but one of them -- involuntary manslaughter in the commission of a lawful act -- includes an added mandatory penalty of five years' jail because a gun was involved in the death.
"If any one of these three people -- Alec Baldwin, Hannah Gutierrez-Reed or David Halls -- had done their job, Halyna Hutchins would be alive today. It's that simple," said special prosecutor Andrea Reeb.
"The evidence clearly shows a pattern of criminal disregard for safety on the 'Rust' film set."
'Fast and loose'
A lengthy investigation has looked at how the live round -- and five others -- got onto the set, and how it ended up in a prop gun.
Speaking on CNN, Carmack-Altwies said the production had a "fast and loose" attitude to safety, with those live rounds mixed in with dummy rounds.
"And then they somehow got loaded into a gun handed off to Alec Baldwin. He didn't check it. He didn't do any of the things that he was supposed to do to make sure that he was safe or that anyone around him was safe.
"And then he pointed the gun at Halyna Hutchins and he pulled the trigger."
The accident sent shockwaves through Hollywood and led to calls for a total ban of real guns on set.
Industry experts have said there are already stringent safety rules that were ignored.
Actors' union SAG-AFTRA said Thursday the charge against Baldwin was "wrong and uninformed."
"An actor's job is not to be a firearms or weapons expert. Firearms are provided for their use under the guidance of multiple expert professionals directly responsible for the safe and accurate operation of that firearm," the union said.
Baldwin last year reached an undisclosed settlement with the family of 42-year-old Hutchins.
It was also announced at the time that production on the movie would restart this year.
Widower Matthew Hutchins will become an executive producer with "all the original principal players" returning to the set.
Souza said he would devote his work on the film "to honoring Halyna's legacy and making her proud."