Os Municipality has decided to take the measure after the swan last Friday attacked a group of daycare children and dragged a girl into the water, according to a report by NRK.
The episode was the latest in a series of attacks which the animal will now pay for with its life, says the report.
Trine Reiertsen of Os Municipality told NRK on Sunday that the swan could potentially be moved from Os Harbour to another location.
But the decision to put down the animal, which is both popular and infamous in the area, has now been made by the authority.
“It's sad, but after the attack on Friday we really have no choice. He has gone over the line now. There have been so many episodes and the attack last week caused people to ask us to do this,” spokesperson Marie Bruaruøy told NRK.
Norway's Nature Diversity Law (Naturmangfaldslova) states that authorities have the right to put down protected species if they are considered a danger to people.
Os Municipality has several times in the past paid veterinary fees to protect the health of the swan, which has lived for several years at the body of water in the municipality near Bergen, reports NRK.
“He has been an institution for many of us, and I can understand why people are fond of him,” Bruaruøy said.
Opinions have long been divided over the swan in the area, she added.
“There's no doubt that the Harbourmaster has been harassed over the years. Many people have witnessed him being treated roughly, teased and chased by boats. That must have contributed to his aggressiveness,” she said.