Riku, Kai, Hanako and Amu had been living in outdated cages at the Ainu Cultural Museum, on the island of Hokkaido, and urgently needed new facilities, according to staff at their new home at the Yorkshire Wildlife Park (YWP).
The South Yorkshire attraction - which has become a second home to scores of animals from lions to polar bears over the last decade - said it stepped in when it became clear there was no capacity in Japanese zoos to take them.
It said a detailed operation was put together over the last two months to ensure a safe 5,400-mile journey to the UK.
YWP animal manager Debbie Porter said: "The loading went like clockwork."
Ms Porter said: "The 27-year-old female Hanako was very playful when we were loading her - at one point she tried to grab a hosepipe, she was very curious about what was going on.
"She is very sassy and extremely bright. She does like people so it should be quite fun when we get her settled at home."
Ms Porter said the bears were taken to the airport in an air-conditioned lorry provided by DHL Japan.
They were flown to Tokyo and then to London, before they were driven to Doncaster where they were released into their new home.
Ms Porter said: "I actually took a photo of the empty cages because you think for 27 years they have been in that tiny caging.
"It was a very emotional day. "
The team said that Hanako was the first to leave her crate and the two younger males - Kai and Riku - were next.
The oldest bear Amu was left quietly for several hours to make his own mind up about coming out of his crate.
They said the bears will spend a few days in their house before being introduced to the expansive reserve beyond it.
John Minion, CEO of the park at Branton, near Doncaster, said: "We are fortunate we have the space, animal management skills and experience to rehome these bears that will require specialist care and it is great to welcome them to Yorkshire.
"We are grateful to the Ainu Museum for releasing the bears to us where we will be able to give them a secure future."
The Ussuri Brown Bears are also known as the Black Grizzly and can weigh up to 550kg and live up to 35 years.
The species is on the IUCN Red List of Threatened Species and there are estimated to be around 10,000 in Japan.