The four-month-old bear cub, called Nastia, was snatched from her mother at the Lutsk zoo in the Volyn province.
She was then brutally forced into a transport box and taken away by car.
Throughout the ordeal, the bear cub screamed and tried to resist, while her mother frantically ran around her cage.
The incident was caught on camera by animal welfare charity Four Paws.
It said that an animal trader has bought Nastia, most likely for use as a ‘photo bear’ in the tourist trade.
“These are the most shocking pictures I have seen in my long career in animal welfare”, said charity boss Amir Khalil.
“It is not just the brutality that was applied that demonstrates the inhumanity seen in this video.
“A baby bear in the wild usually stays with their mother for two years. When taken away from her too early, the cub remains traumatised and suffers from a lack of real socialisation.”
‘Photo bears’ are put on a lead and placed in front of tourists who want to have photos taken with them.
Selling animals from zoos to private buyers is illegal in the Ukraine, and Mr Khalil urged the government to confiscate the young bear.
“There’s no time to lose. This mother and child need to be reunited as quickly as possible. We are at the full disposal of the authorities and need to establish a home for both bears, appropriate for the species.”
The charity says there are more than 80 brown bears held captive in poor conditions across Ukraine.