The Soyuz, which began its return journey to Earth by separating from the International Space Station at 2149 GMT on Monday, landed safely on the steppes of Kazakhstan in Central Asia at 0109 GMT on Tuesday, a spokesman for the centre said.
The third civilian in history to pay for a space flight, arranged by Space Adventures, the sole space travel agency in operation, had travelled home with US astronaut John Philips and Russian cosmonaut Sergei Krikalev.
"The three are well and in good spirits," the spokesman said after the three landed safely, to be wrapped by the centre's officials who had opened up the capsule in fur-line sleeping bags to protect them from the cold.
Krikalev and Philips had been aboard the ISS since 17 April.
They were replaced by American William MacArthur and Russian Valery Tokarev, who lifted off with their space tourist from Baikonur in Kazakhstan for the ISS space station 1 October.
Olsen, 60, paid Space Adventures $20 million for a seat aboard the capsule and eight days of gazing down at the Earth from the ISS station, 370km up.
The space station is parked permanently in space and manned by a succession of teams relieving each other at regular intervals.
Olsen spent 1500 hours preparing for his mission at a space base near Moscow and at Baikonur.
He was preceded into space by two other millionaire tourists, American Dennis Tito in 2001, followed by South African Mark Shuttleworth the following year.
The Soyuz TMA-7 space vehicle
in which Olsen spent eight days
During his eight-day journey aboard the ISS Olsen planned to test equipment developed by his company, a New Jersey-based firm that makes electronic sensors for military and civilian use.
Ground officials established radio and visual contact with the craft about five minutes before the scheduled landing around dawn on Tuesday on the broad, empty steppes of Kazakhstan, where Russia's manned-space facilities are based.
Four search planes and 17 helicopters scrambled to meet the spacecraft.
Search-and-rescue crew members in camouflage military uniforms and white medical coats helped the men out of the capsule, sat them in chairs and draped blankets and fur-lined parkas over their shoulder to ward off the early dawn chill.
Rescuers reported that the crew's condition was "good," according to Russian Mission Control at Korolyov outside Moscow.
Olsen grinned ebulliently, ate a green pear and drank water with gusto as he chatted with ground personnel.
"This shows us how to fight for your dreams. He fought, he won, he passed the entire flight, all the preparations to become an astronaut, superbly," Anatoly Perminov, chief of the Russian space agency, said at Mission Control.
"He fought, he won, he passed the entire flight, all the preparations to become an astronaut, superbly"
Russian space agency chief
But returning American astronaut John Phillips appeared to be less responsive, and rescuers repeatedly waved a small bottle of smelling salts under his nose, causing him to jerk back his head, and wiped beads of sweat away from his forehead and eyeglasses.
Mission Control officials said it was normal for returning astronauts and cosmonauts to slip in and out of consciousness after the rough ride through space.
A Russian Space Agency official said that Japanese businessman Daisuke Enomoto was in line to be the world's fourth space tourist, following Olsen, fellow American Dennis Tito and South African Mark Shuttleworth.
Alexei Krasnov, the head of manned programmes, said in an interview posted on the agency's website that the Japanese could face a challenge by another American, whom he did not name.
"Whoever is better prepared will fly," he said, adding that the next space tourist probably would not travel to the ISS until autumn 2006.
The Soyuz spacecraft and Russia's unmanned Progress cargo ships have been the ISS' lifeline since the US space shuttle Columbia disaster in 2003.
The European CyroSat satellite
was lost due to rocket failure
The shuttle programme was suspended for more than two years; the shuttle Discovery flew to the ISS in July, but problems with its insulation raised doubts about when the next shuttle would go into space.
Russia's space programme, despite chronic funding problems, has enjoyed the image of reliability in recent years.
But that reputation was tarnished over the past week by a pair of failed unmanned missions, including the loss of the estimated $210 million CryoSat European satellite due to the failure of a Russian Rokot booster.
That dealt a major blow to the European Space Agency, which had hoped to conduct a three-year mapping of polar sea ice and provide more reliable data for the study of global warming.