The actor was dressed in a dark blue suit, light blue shirt and pink tie as he was called by his full name and asked if he was Kevin Spacey Fowler.
"I am," he said as he stood behind a window in the dock.
Spacey, 63, has pleaded not guilty to a dozen charges including sexual assault, indecent assault and causing a person to engage in sex activity without consent. He could face a prison sentence if convicted.
Spacey has said an acquittal in the case could revive a career that has largely been on ice since sexual misconduct allegations surfaced against the star who won his first Academy Award for supporting actor in "The Usual Suspects" in 1995.
"There are people right now who are ready to hire me the moment I am cleared of these charges in London," Spacey said in a rare interview published this month in Germany’s Zeit magazine. He said the media had turned him into a "monster."
The charges involving men now in their 30s or 40s date from 2001 to 2013 — covering most of the decade when he lived in Britain and served as artistic director of the Old Vic Theatre until 2015.
Jurors were to be selected on the first day of the trial and opening statements are scheduled Friday.
The actor, who is free on bail, arrived at London’s Southwark Crown Court about two hours before the trial was due to start.
Spacey's downfall came amid the #MeToo movement in the United States when allegations led to him being written off the Netflix political thriller "House of Cards," where he played lead character Frank Underwood, a ruthless and corrupt congressman who becomes president. He was cut from the completed film "All the Money in the World," and the scenes reshot with Christopher Plummer.
Spacey became one of the most celebrated actors of his generation in 1990s, starring in films including "Glengarry Glen Ross" and "LA Confidential." He won his second Oscar, for best actor, in the 1999 movie "American Beauty."
Spacey recently had his first film roles in several years, appearing in 2022 in Italian director Franco Nero’s "The Man Who Drew God," and playing the late Croatian President Franjo Tudjman in biopic "Once Upon a Time in Croatia." He also stars in the unreleased U.S. film "Peter Five Eight."
Italy’s National Cinema Museum in Turin gave him its lifetime achievement award in January. He also taught a masterclass and introduced a sold-out screening of "American Beauty" in what were billed as Spacey’s first speaking engagements in five years.
Spacey saluted organizers for "making a strong defense of artistic achievement" and for having "le palle" — the Italian word for male body parts synonymous with courage — to invite him.
Associated Press writer Jill Lawless contributed to this report.