On July 22nd, 2011, neo-Nazi Anders Behring Breivik carried out the two attacks, first killing eight people by detonating a bomb at the foot of a government building in Oslo.
He then killed 69 others by opening fire at a Labour Party youth camp on the island of Utøya, with the teenagers trapped by the waters of the surrounding lake.
The attacks were the worst committed on Norwegian soil since World War II.
A memorial to the victims was unveiled at 10am on Sunday, the seventh anniversary of the murders, at Johan Nygaardsvolds plass in Oslo.
The names and ages of each of the victims are inscribed on the memorial, which resembles broken glass as a symbol of the damage caused by the bomb in the Norwegian capital.
Prime Minister Erna Solberg was among those who spoke at the unveiling and memorial ceremony on Sunday.
“Seven years sounds like a long time, but many still live every day with what happened on July 22nd,” the PM said according to NRK's report.
The names of each of the victims were read out following Solberg's and the other speeches.
Manu Hussaini, leader of the youth wing of the Labour Party, said that Norway had a duty to be there for the survivors and those living with the loss of loved ones.
“Let us use this day to see each other. To see all those who need help and care, an extra hug or a shoulder to cry on,” Hussaini said in his speech.
Other speakers included Lisbeth Kristine Røyneland, the leader of the national group for support of July 22nd victims, and Tor-Inge Kristoffersen, a member of the group.
Jonas Gahr Støre, leader of the Labour Party, stressed the importance of a memorial in Oslo's Regjeringskvartalet, the area where the Oslo attack was committed and which is home to many official buildings.
“It is like a gravestone and a collective memorial for those who lost loved ones. It is also a part of Norway's history,” Støre told NTB.
The memorial in Oslo is officially temporary, with authorities currently not at consensus as to how the tragedy will be permanently marked at Utøya.