Spacey arrived at London's Westminster Magistrates' Court at around 10 a.m. on Thursday morning and was greeted by throngs of photographers and members of the media as he made his way into the building.
Spacey made no comment to the media on his way to court and the proceedings are not open to the public.
The Metropolitan Police formally charged Spacey, 62, on Monday.
The U.K.'s Crown Prosecution Service in May had authorized the charges against the Academy Award-winning actor, saying they stemmed from alleged incidents in London and Gloucestershire over a period of about eight years.
Prosecutors in May detailed four sexual assault charges linked to two alleged assaults against the same man in March 2005, and two alleged assaults against separate men in August 2008 and in April 2013. The final charge was linked to an alleged incident in August 2008, against the same man Spacey was alleged to have assaulted that same month, prosecutors said.
"The CPS has also authorised one charge of causing a person to engage in penetrative sexual activity without consent," Rosemary Ainslie, head of the Special Crime Division, said in a statement at the time. "The authority to charge follows a review of the evidence gathered by the Metropolitan Police in its investigation."
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Prosecutors said it was "extremely important" that there be "no reporting, commentary or sharing of information online which could in any way prejudice these proceedings."
"The Crown Prosecution Service reminds all concerned that criminal proceedings against Mr. Spacey are active and that he has the right to a fair trial," Ainslie said in a statement.
Spacey, who served as artistic director of London's Old Vic theater from 2004 until 2015, told "Good Morning America" in late May that he would "voluntarily" appear in court in London.
"I very much appreciate the Crown Prosecution Service's statement in which they carefully reminded the media and the public that I am entitled to a fair trial, and innocent until proven otherwise," Spacey told "GMA" in May. "While I am disappointed with their decision to move forward, I will voluntarily appear in the U.K. as soon as can be arranged and defend myself against these charges, which I am confident will prove my innocence."