Brett De La Mare, a 36-year-old Australian, came to earth on the parade ground in front of the building at about 1:00 pm (1300 GMT) and was immediately held by police.
There were no members of the royal family in the building at the time as they are spending the Christmas holiday at their Sandringham Estate in Norfolk, eastern England.
Police sources said there was no threat to security at the palace and that the incident was a publicity stunt. De La Mare's flatmate, Monica Kelly, said he was trying to drum up interest in his unpublished novel.
A Scotland Yard spokesperson said: "Officers from the Royal Diplomatic Protection Group arrested a man who descended into the forecourt in a motorised paraglider."
"He is being questioned by detectives and detained at a central London police station."
A Buckingham Palace spokespersonn said the paraglider circled Buckingham Palace several times before setting down in front of the building, in the area normally used for the changing of the guard ceremony.
The forecourt has tall iron railings running along one side of it to keep the public out.
"He certainly did not have permission to land on the forecourt. I think he was surprised by the vigour and speed of the police response," said the palace spokesperson.
The paraglider was tailed for the last few miles by a police helicopter, which had spotted its approach and notified officers on the ground.
It is not the first time an intruder has got into the heavily-guarded grounds of Buckingham Palace from the air.
American paraglider Jim Miller landed on the roof of the palace in 1994. His stunt was even more bizarre because he performed it naked.
The most serious breach of security at the palace was in 1982, when Michael Fagan, from north London, scaled the palace walls at night and broke into the Queen's bedroom.
She woke to find him sitting on her bed. She had the presence of mind to keep the intruder talking until guards arrived to take him away.
German tourist Eric Schmidt, 57, was outside Buckingham Palace on Thursday afternoon when De La Mare landed in his paraglider.
"I suddenly heard the helicopter and looked up and saw the man in a parachute," he said. "The helicopter was going towards him and he was being given a warning on a loudspeaker, but the man did not seem to take any notice."
"He landed running on his feet behind the gate and he was quickly whisked away by police."
According to De La Mare's own website, he has performed a similar stunt in New York in a bid to get a publishing deal for his novel, called Canine Dawn, which he described as a racy tale of "sex, money and adventure" set in the Australian bush.
"I'm prepared to do whatever it takes to get noticed," he said on the website. "I'm not crazy, just broke and desperate. I need a publishing deal." - Sapa-AFP