Missouri Governor Eric Greitens has been charged with felony invasion of privacy in connection with an inquiry into his extramarital affair.
The woman alleges that he tied her up, photographed her and threatened to release the image if she ever revealed their trysts.
The Republican, who was taken into custody on Thursday, maintains his innocence, said his lawyer.
Mr Greitens admitted last month he had a relationship with his hairdresser.
Critics have called his alleged actions “revenge porn” and blackmail.
The charge sheet alleges Mr Greitens took a picture of the unidentified woman in “full or partial nudity” without her knowledge or consent.
It further alleges that he transmitted the image “in a manner that allowed access to that image via a computer”.
St Louis Circuit Attorney Kim Gardner vowed in a statement on Thursday to “hold public officials accountable in the same manner as any other resident”.
But Mr Greitens’ lawyer, Edward Dowd, told local media: “In forty years of public and private practice, I have never seen anything like this.
“The charges against my client are baseless and unfounded. My client is absolutely innocent. We will be filing a motion to dismiss.”
The woman’s then husband secretly recorded her in March 2015 describing the otherwise consensual encounter at Mr Greitens’ home in the city of St Louis.
She told her now ex-husband in the audio recording that she “saw a flash through the blindfold and he [Mr Greitens] said, ‘You’re never going to mention my name'”.
A lawyer for the unnamed man also alleges his then wife was slapped by Mr Greitens during a 2015 encounter in hospital as Mr Greitens’ own wife was giving birth.
“When she admitted that she’d had sexual relations with her husband during a period of reconciliation, the governor slapped her,” attorney Albert Watkins told CBS News last month.
In January Mr Greitens acknowledged the affair, saying he had made “a personal mistake” and was “sorry for the pain it caused to everyone impacted”.
He said he and his wife, Sheena Greitens, were moving on from the episode and wanted to deal with it privately.
Mr Greitens, a former special forces soldier and father-of-two, took office in 2016 with a pledge to tackle corruption.
He described himself during his campaign as a “Navy SEAL, native Missourian and most importantly, a proud husband and father”.