The Oslo service, run by bmi, operates as a single daily flight Sunday to Friday with a 37-seat Embraer 135 jet aircraft.
The same airline launched direct flights between Aberdeen and Kristiansund in the south west of Norway at the end of August.
From January it will also operate direct flights between Stavanger and Harstad/Evenes and Tromso in the far north of Norway.
The airline says it means bmi regional will be the first non-Scandinavian airline to launch scheduled domestic flights in Norway.
Cathal O'Connell, chief executive of bmi regional, said: "Aberdeen and Oslo are strategic hubs for the oil and gas industry and our new service will offer significant time and efficiency savings for businesses in the North-east of Scotland and Norway."