Jakobsson is from Iceland, where he swam for Frjálsíþróttafélag ÍBV [is] (until 2012 called Ungmennafélagið Óðinn) in the Vestmannaeyjar,[2] later for Íþróttabandalag Reykjanesbæjar in Reykjanesbær.

[4] In April 2012 Jakobsson was one of two team-mates sharing a room with Alexander Dale Oen at a training camp in Flagstaff, Arizona, who discovered him dead in the bathroom;[14][15][16] both withdrew from swimming for several months.

[21] At the 2014 European Aquatics Championships, for which he was selected despite not having technically qualified,[22] he again broke his own previous Norwegian record for the 200 metre butterfly, with a time of 1.59.80.

[27] In 2016 he won 13 gold medals, seven individual, at the Norwegian Short Course Championships,[9] and again set a new record for the 200 metre butterfly, 1.58.85, at the Bergen Swim Festival.

[28][29] Jakobsson set a Norwegian senior record of 1.58.93 in the 200 metre butterfly at the 2016 European Aquatics Championships,[30][31] but did not qualify for the 2016 Summer Olympics.