Saberi, who has worked for the BBC and U.S. National Public Radio, was released one day after a Tehran court held a hearing on her case that was closed to the public.
Iranian President Mahmoud Ahmadinejad last month called for Saberi to be given full legal rights to defend herself and Foreign Minister Manouchehr Mottaki said her sentence would be reviewed based on "human and Islamic kindness."
"I'm very satisfied and happy about the ruling. We expected her to be freed but not this soon," said Reza Saberi, 68, who came to Tehran last month with his Japanese wife Akiko to follow their daughter's case.
One of her defense lawyers, Saleh Nikbakht, told the ISNA news agency the court had acquitted her of spying but sentenced her under a law covering violations including taking pictures or videotaping in areas where photography is banned.
She would be banned from doing any reporting work in Iran for five years, her main lawyer, Abdolsamad Khorramshahi, said.
Saberi, a former Miss North Dakota, looked thin and tired at Sunday's court session. Last week, her father said she had ended a two-week hunger strike and was "very weak." The judiciary denied she had refused food and said she was in good health.
Tehran, which does not recognize dual nationality, said throughout the case that Washington should respect the independence of Iran's judiciary.
