The man and woman were hiking at around 8pm on Friday in the Red Deer River Valley, west of Ya Ha Tinda Ranch, when they encountered the bear, according to authorities.
The bear attacked the couple, who died from their injuries. Their pet dog also died in the attack.
Parks Canada said that it received an alert from a GPS device in the region, which is located three hours’ north of Banff town.
Harsh weather then initially hindered rescue teams from reaching the couple, according to Natalie Fay, from Park Canada’s Banff field unit.
“Weather conditions at the time did not allow for helicopter use, and the response team travelled through the night to the location by the ground,” she said.
“The response team arrived on-site at 1 am and discovered two deceased individuals.
“This is a tragic incident and Parks Canada wishes to express its sincere condolences to the families and friends of the victims.”
The bear was later euthanised “to ensure public safety” after displaying aggressive behaviour to the rescue teams.
Royal Canadian Mounted Police (RCMP) later transported the victims’ bodies to the town of Sundre in the early hours of Saturday morning.
The victims have not been publicly named but CBC News spoke to a family member who said the couple were experienced with the outdoors.
A statement from the family read: “They were long-term partners who loved the outdoors and were inseparable.
“They lived for being in the backcountry and were two of the most cautious people I know. They knew bear protocol and followed it to a tee.”
According to the family member, the couple “checked in every night” when they were away.
“This means they were not travelling after dark and they were not setting up camp when the attack happened,” they said.
The area surrounding Red Deer and Panther Valleys remains closed until further notice.
There are believed to be just 60 grizzly bears in Banff National Park and the population is considered to be under threat in Alberta.