Wearing his trademark dapper suit and sunglasses, the rapper attracted a horde of fans and photographers as he walked into the 189-year-old Oxford Union club.
Asked by reporters at the entrance how it felt to be in the historic city, the 34-year-old said, "It's an honour," before adding: "It's kind of weird -- why did they call me?"
Psy, whose single "Gangnam Style" has more than 665 million views on YouTube and has spawned countless videos copying his distinctive dance moves, arrived in Britain from France on Monday for a three-day visit.
Former boxing champion Chris Eubank was among the crowds that turned out to greet him in Oxford.
The rapper, whose full name is Park Jae-sang, was invited to address the Oxford Union by its president John Seung-yoon Lee, who is also South Korean.
"The president and Psy are both from Gangnam -- the area (of the South Korean capital Seoul) where the eponymous hit song takes its name," a spokesman for the debating society said.
Psy is already an established star in South Korea with six albums under his belt, but the song -- which parodies the extravagant lifestyle of the residents of Gangnam -- has turned him into a global star.
His address to the Oxford Union, due later on Wednesday, was to be his first public speech in English.
The debating society's previous guests include US presidents Richard Nixon, Jimmy Carter and Ronald Reagan, the Dalai Lama and Mother Teresa.
On Monday, a flash mob of some 20,000 fans joined Psy in Paris to perform his "horse-riding dance".
His new album is set to feature a new single half in Korean, half in English and a selection of songs from his 12-year career in his home country.
South Korea awarded Psy on Tuesday with one of its highest cultural honours, the Okgwan Order of Cultural Merit, as a reward for taking the world by storm.