Reports said O'Donovan spent Friday night in a cell at the Harare Central Police Station and she faced the courts this Saturday.
Her attorney, Rose Hanzi, has said the charge is illegal due to the fact that police didn't inform O'Donovan of it when she was arrested at her home on Friday.
The charge of subversion carries up to 20 years in prison.
According to the AP, the NYU grad has been charged with subversion and insulting the president.
O'Donovan's lawyer, Obey Shava, says police have not yet charged her but they claim that "tweets emanating from her IT address are insulting to the president".
The ZRP officers, who arrested O'Donovan, were armed with a search warrant, which was granted on Thursday 02 November 2017 by Harare Magistrate Elisha Singano authorising the law enforcement agents to confiscate all her electronic devices as they reportedly investigated a case of undermining authority of or insulting President as defined in Section 33 of the Criminal Law (Codification and Reform) Act.
O'Donovan has denied the allegations as "baseless and malicious".
Last month, Mugabe appointed a "cybersecurity minister", ostensibly to crack down on social media criticism of the government.
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Social media posts played a major role in fueling major anti-government protests in Zimbabwe past year.
American woman Martha O'Donovan has appeared in a Zimbabwean court accused of attempting to overthrow the country's government on charges that carry a maximum penalty of 20 years' jail.
The lawyer says O'Donovan has worked with local social media outlet Magamba TV, whose target audience is youth.
Zimbabwe Lawyers for Human Rights says it has represented almost 200 people charged for allegedly insulting Mugabe, the world's oldest head of state, in recent years.
"This arrest marks the start of a sinister new chapter in the Zimbabwean government's clampdown on freedom of speech, and the new battleground is social media", Muleya Mwananyanda, Amnesty International's deputy regional director stated.
Shava is part of Zimbabwe Lawyers for Human Rights who often represent activists that are arrested in that African country.
"Concerned to hear of Martha O'Donovan's arrest and ongoing detention".