Andrew Tate, a notorious British-American influencer, will be detained in Romania for 30 days after a judge granted a police request.
Tate and his brother Tristan were arrested on Thursday local time as part of an investigation into human trafficking and rape charges, which they deny.
The government suspects the pair and two Romanian individuals of operating "an organized crime group."
The court in Bucharest also detained Tristan and two others.
Eugen Vidineac, the Tates' attorney, stated outside of court that they would fight the imprisonment.
"We are not at a stage where guilt or innocence is proven; for now, we only discuss preventive measures," he added. Vidineac informed the BBC that his clients deny all claims.
Andrew Tate, 36, has not yet directly commented on the allegations.
But after being imprisoned, he tweeted a reference to the 1999 film The Matrix via his Twitter account.
The message stated that agents from The Matrix had been dispatched. Additionally, the account retweeted Matrix memes created by Elon Musk, the owner of Twitter.
Their attorney told the BBC that the two brothers exercised their right to remain silent throughout the detention hearing.
Previously, a police official told the BBC that the 36-year-old would be detained in a "detention center."
Romania's Directorate for Investigating Organized Crime and Terrorism published a statement Thursday night, without naming the Tate brothers, indicating that two British people and two Romanian citizens were accused of being a part of a human trafficking network.
The statement said that authorities had identified six individuals who had allegedly been "sexually exploited" by an "organized criminal group."
The police stated that the British nationals "recruited" the victims by misrepresenting their intention to enter into a romantic connection with them, a tactic dubbed "the loverboy method."
The statement said that they were later forced to perform in pornographic content under threat of assault.
Tate, born in the United States before relocating to the United Kingdom, had a successful kickboxing career.
In 2016, he was booted from the British reality television show Big Brother when a video purported to depict him assaulting a woman. Then, he established a webcam business, which he termed "adult entertainment."
As a result of his statement that women should "bear responsibility" for sexual assault, Twitter banned him from the platform. Musk subsequently reinstated him.
However, despite social media bans, he garnered popularity, especially with young men, by preaching an ultra-masculine, ultra-luxurious lifestyle.
He was often featured in videos with a fleet of costly sports vehicles, private jets, and extravagant vacations.