In August 2019, Atli left the club to join Fredrikstad FK of the Norwegian First Division.
[2] He appeared in the team's single 2020–21 UEFA Europa League match, a 1–2 elimination defeat to NK Olimpija Ljubljana of the Slovenia PrivaLiga.
[5] On 27 January 2022, it was confirmed that Atli had joined Danish Superliga club SønderjyskE on a deal until 30th of June 2026.
[6] On August 19, 2024, Belgian Challenger Pro League club Zulte Waregem confirmed that they had signed Barkarson on a deal until 30th of June 2026.
[7] Atli was called up to the senior national team for a friendlies against Uganda and South Korea in January 2022.