The arrest occurred hours after the Seoul Central District Court reviewed the prosecutors’ request for an arrest warrant against the 52-year-old.
The court granted the warrant, citing the risk of tampering with evidence, after prosecutors submitted an 848-page opinion laying out Kim’s alleged “unlawful acts”.
With the arrest, South Korea now has a former president and first lady both behind bars for the first time in the nation’s history.
The charges against Kim include violations of capital market and financial investment laws, as well as political funds laws.
The arrest caps a dramatic fall for the ex-first couple after former president Yoon Suk Yeol’s stunning martial law declaration on December 3, which saw soldiers deployed to parliament but was swiftly voted down by opposition MPs.
Yoon, a former top prosecutor, was impeached and removed from office in April over the martial law declaration, prompting the country to hold a snap election in June.
He has been under arrest and in detention since July 10.
Last week, Kim underwent hours-long questioning by prosecutors, who filed for her arrest warrant the next day.
“I sincerely apologise for causing trouble despite being a person of no importance,” Kim said as she arrived at the prosecutors’ office on Wednesday.
Controversy has long surrounded Kim, with lingering questions about her alleged role in stock manipulation.
Public criticism was reignited in 2022 when a left-wing pastor filmed himself presenting her with a Dior handbag that she appeared to accept.
She is also accused of interfering in the nomination process for MPs in Yoon’s party, a violation of election laws.
Yoon, as president, vetoed three special investigation bills passed by the opposition-controlled parliament that sought to probe the allegations against Kim, with the last veto issued in late November.
A week later, Yoon declared martial law.
Mug shot
Under prison regulations, Kim will have to change from her normal clothes into a khaki prison uniform and be assigned an inmate number.
She will also have to take a mug shot.
The ex-first lady is being held in a 10-square-meter (107-square-feet) solitary cell that has a fan but no air-conditioning, as a heat wave grips South Korea.
According to the prison’s official schedule, she was offered a regulation breakfast including bread, jam and sausages.
Local media reported that her cell includes a small table for eating and studying, a shelf, a sink and a toilet, but no bed.
While she would typically have been held at the same detention centre as her husband, prosecutors on Monday requested that she be detained at a separate facility about 20 kilometres (12.5 miles) away.
Upon the issuance of the warrant, the first lady’s Presidential Security Service protection was terminated immediately.
Kim can be held for up to 20 days as prosecutors prepare to formally indict her, legal expert Kim Nam-ju told AFP.
“Once Kim is indicted, she could remain detained for up to six months,” said lawyer Kim Nam-ju.
The former first lady can challenge the warrant in court as unlawful, “but given the current circumstances, there appears to be a high risk of evidence destruction, making it unlikely that the warrant will be revoked and the individual released,” he added.
“Another option is bail, but this too is not granted if there are concerns about the destruction of evidence.”
