Trams and buses were forced to stop as the pink bird wandered around the city's Casinoplatz square, according to eyewitnesses.
Police managed to divert the flamingo off tram tracks but then needed half an hour to catch the animal.
It later emerged the bird was an escapee from the city's Dählhölzli animal park.
Dählhölzli director Bernd Schildger said he wasn't sure why the flamingo had decided to go on an evening excursion into the city.
"The scientific literature indicates flamingos stay in a group," he told regional daily Berner Zeitung. When several birds remain in the same location for a period of time, the other animals stick around too.
"We have around 40 years' experience with flamingos and that's what we have seen. Obviously, this flamingo has not read the literature," the animal park director said.
Schildger added it was currently not possible to clip the wings of flamingos at the animal park as the animals were brooding and could not be disturbed.
He told Swiss news portal 20 Minuten that around 20 to 30 percent of the flamingos at the park had their wings clipped, and this was generally sufficient to deter other birds from flying away, even though they were perfectly capable of doing so.
Read also: Swiss joggers frighten baby llama to death