The RZSS said: "We are sad to share the loss of Victoria, the UK's oldest polar bear, who was experiencing age-related health problems and had been receiving geriatric care.
"Taking into account her quality of life and wellbeing, our wildlife conservation charity's vets advised that Victoria should be put to sleep."
It added: "She leaves an incredible legacy through her cubs who play an essential role in the European breeding programme, which ensures a healthy and genetically diverse population of these bears living in human care."
Victoria was born in 1996 at Rostock Zoo in Germany and had previously given birth at Aalborg Zoo in Denmark in 2008.
While at Aalborg she gave birth to a female cub called Malik.
She arrived at RZSS' Highland Wildlife Park in March 2015.
During Victoria's later care, RZSS drew on the experiences of other zoos and studies of polar bear skeletal remains to help understand wear and tear on the animals' bodies.
Healthcare provided to domestic cats and dogs also helped guide the care of Victoria.
The park has had an elderly polar bear before.
Mercedes died at the park in April 2011 at the age of 30.
