The 2020 1. divisjon (referred to as OBOS-ligaen for sponsorship reasons) was a Norwegian second-tier football league season.
Lillestrøm, Tromsø and Ranheim were relegated from the 2019 Eliteserien, while Stjørdals-Blink, Grorud and Åsane were promoted from the 2019 2. divisjon.
The 3rd to 6th placed teams took part in the promotion play-offs; these were single leg knockout matches.
The winner of the second round then met the 3rd placed team on away ground.
The winner of the third round advanced to play the 14th placed team in Eliteserien on neutral ground in the Eliteserien play-offs for a spot in the top-flight next season.