Dugard expressed solidarity with Smart, 30, who was kidnapped in 2002 from her bedroom in Salt Lake City and held prisoner by Wanda Barzee and her husband, Brian David Mitchell.
"Wanda Barzee is clearly equally responsible for their actions and she should not be allowed to send a message that her actions are excusable," Dugard told ABC News in an exclusive statement.
Dugard, 38, said she feels "deeply for what Elizabeth is going through knowing this dangerous person is free to walk the street."
"Believe Elizabeth when she says this woman is a threat to society," she added.
Dugard was 11 when she was kidnapped by Phillip and Nancy Garrido in 1991 near her Lake Tahoe, California, home. She was held captive for 18 years and gave birth to two daughters, fathered by Phillip, while she was their prisoner.
Dugard said that what many have characterized as an early release is especially chilling because her own captor, Phillip Garrido, was released early from prison prior to when he kidnapped her.
"Wasn't a lesson learned from my case, when Phillip was released from prison early in his first rape and kidnapping conviction?" she said. "He was then free to take me with his wife's help."
She added that she believes Barzee is "just as guilty" as her husband, "and deserves to serve the same amount of time."
In a news conference late last week, Smart expressed shock at what she said was Barzee's early release, and urged authorities to "really strongly reconsider this situation, to look at all the facts, look at her mental status, and see if they really and honestly truly feel that she is no longer a threat."
"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 she was being raped, but to encourage her husband to continue to rape me," Smart said.
Barzee, 72, is set to be released from prison on Wednesday, according to the Associated Press.
She was previously scheduled to be released in January 2024, and the Utah Board of Pardons and Parole denied her an early parole at a hearing in June of this year, the AP reported.
But Barzee was convicted on both state and federal charges, and her attorney, Scott Williams, argued that time she had already served in federal prison must be credited towards her state conviction, according to the Salt Lake City Tribune. The board agreed, and moved up her release date on Tuesday.
"The Board has heard concerns and requests to reconsider releasing Wanda Barzee," the Utah Board of Pardons and Parole said in a statement on Thursday. "This is not an early release or a discretionary release. On September 19, Ms. Barzee will have spent 15 years in custody, which is the maximum amount of time allowed by her state conviction and sentence. Ms. Barzee cannot legally be held in the Utah State prison beyond the length of her sentence."
ABC News' Azure Gilman, Sean Dooley, Tess Scott, Christina Ng and Lauren Effron contributed to this report.