In the final match of the season against Valur, Pétursson scored the winning goal which got KR into European football.
He was considered to have quite some potential, playing 7 games and scoring 2 goals, which got him a loan offer from Sandefjord on 31 August 2007.
With KR he won the VISA Bikar 2008, coming off the bench as a substitute in the final against Fjölnir.
On 18 July 2009, Pétursson went on loan to Breiðablik where he grew to become an important asset to the team.
Breiðablik went all the way to win the VISA Bikar 2009 which meant Pétursson's second Cup title in 2 years.
[4] The former ÍR, KR and Sandefjord player rejected an offer from Icelandic champions FH, and chose to join Breiðablik, after a successful loan-spell in 2009.
The game after that Pétursson was back in the starting line-up again and thanked his manager by scoring a goal in the 3–1 victory against Selfoss.
Pétursson played his 100th official career league game when Breiðablik slaughtered Stjarnan 4–0 at home on 8 July.