A rescue team tranquilized the mother after failing to steer her toward a nearby forest, officials said.
Residents had reported that the bear and her cub were wandering through gardens and breaking fences in search of food in downtown Brasov. Traffic was stopped for two hours as a team tried to get the animals back to the wilderness.
"The bear cub was very small and could not keep up with its mum, and she did not want to go back to the forest without it," said Flavius Barbulescu, head of the animal protection service.
The animals finally took refuge in a building, climbing the stairs to the attic, breaking a window and then clambering onto the roof. "That was when we decided to tranquilize the mother," Barbulescu said.
Rescuers shot the bear with a dart gun. Once she was asleep, they removed her and her cub from the roof and took the pair to the zoo in an operation shown live on TV. Officials said the animals would be sent to a nearby bear reservation.
Brasov, some 150 kilometers (95 miles) northwest of Bucharest, is one of Romania's largest cities and a very popular tourist destination. Sightings of bears are common, especially in the district of Racadau, where the animals rummage through garbage container in search for food.
Thursday's adventure was the second in recent weeks in downtown Brasov. Romania is home to about half of Europe's brown bears.
