The 2018 2. divisjon (referred to as PostNord-ligaen for sponsorship reasons) was a Norwegian football third-tier league season.
The following teams changed division since the 2017 season.
The teams who finished in second place in their respective group qualified for the promotion play-offs, where they faced each other over two legs.
The winner, KFUM Oslo, then played against the 14th placed team in 1. divisjon for a place in the 2019 1. divisjon.
KFUM Oslo won 4–1 on aggregate.