Female brown bear Schnute was put to sleep on Sunday, a spokesperson for Berlin Mitte district authority told DPA.
"We're extremely sad that Schnute had to be put to sleep, but it was the right decision, as an animal should never be in pain," Christa Junge, chairperson of Berliner Bärenfreunde e.V told The Local.
"Schnute will remain unforgettable to both Berliners and bear-lovers across the world."
Schnute was the last bear to live in Berlin's Köllnischer Park – a home which for years faced fierce protests by animal rights campaigners in the city.
"With Schnute's death, 76 years of keeping bears in Berlin's city centre comes to an end," said Junge.
Opened in 1939, the compound has housed brown bears - the city's symbolic guardians depicted in its coat of arms - for decades.
But the compound was nowhere near big enough for an adult brown bear, protesters claimed when they occupied the compound in 2012.
Schnute lived with daughter Maxi until the younger bear's death in 2013.
After Maxi's death, animal rights campaigners renewed calls to have Schnute removed from the compound as soon as possible, and transferred to a more spacious enclosure.
Junge disputed claims that the enclosure was inappropriate.
"Schnute was an old bear," she told The Local. "After Maxi's death she had a 480-metre-square enclosure all to herself."
The compound was made age-appropriate for the bear, Junge said - adding: "she was often seen snuffling around, scraping in the bark mulch with her paws and finding things to eat."
When Maxi died, they didn't want to send Schnute to a bear park, Junge explained.
"You can always improve conditions for older bears on-site, and that's what has been done here" she told The Local, adding that the team had accepted advice on Schnute's living conditions from well-known experts.
Schnute remained in the compound until her death on Sunday.
In her old age, she suffered from numerous health complications, including arthritis.
By Hannah Butler