The 19-year-old will join team-mate Duncan Watmore as the second Black Cats player to move north of the Border today after the winger joined Hibernian on loan earlier.
Moberg Karlsson’s only competitive first-team appearance came in the 4-2 win over Milton Keynes Dons in the Capital One Cup second round.
The Sweden U19 international joins Watmore, Modibo Diakite and David Vaughan as the players to leave the club today either permanently or on loan.