The Utah Department of Corrections announced Barzee, 72, was released at 8 a.m. MDT.
Barzee was found guilty of helping her husband, street pastor Brian David Mitchell, abduct then-14-year-old Smart from her Salt Lake City home. The case drew international attention and Smart was spotted walking with the couple nine months later. Mitchell and Barzee were arrested and tried for the kidnapping.
Mitchell, who had previously done odd jobs at the Smart family home, is serving a life sentence on kidnapping and rape charges.
Barzee was convicted and sentenced to 15 years in prison in 2010. She received credit for time already served and was released from federal prison in 2016, but faced a state prison sentence until 2024 for a separate attempted abduction of Smart's cousin.
A request by Barzee's attorney to count her time in federal prison toward the state jail term was initially denied, and then reversed, with the state parole board saying it discovered part of Barzee's federal prison time should count toward her state sentence. The decision allowed Barzee to be freed on Wednesday.
Officials last week announced Barzee's impending release, which angered Smart, now 30, and her family. Smart called Barzee a continued threat to the public who should stay in prison.
"I do believe she's a threat. For me, I know the depth of her depravity," Smart said. "She is a woman who had six children and yet could co-conspire to kidnap a 14-year-old girl and not only sit next to her while being raped but encouraged her husband to continue to rape me."
Barzee will remain on federal probation for five years and must undergo a mental health assessment, which she refused to do while in state prison. Her release conditions also include no involvement with the Smart family.
U.S. Attorney John Huber said last week the government has a "range of remedies" if Barzee violates her probation.