Leirfjord is a municipality in Nordland county, Norway. It is part of the Helgeland traditional region. The administrative centre of the municipality is the village of Leland. Other villages in Leirfjord include Bardalssjøen and Sundøy. The large Helgeland Bridge is partly located in the municipality, connecting it to Alstahaug Municipality and the town of Sandnessjøen.

Helgeland is the most southerly district in Northern Norway. Generally speaking, Helgeland refers to the part of Nordland county that is located south of the Arctic Circle. It is bordered in the north by the Saltfjellet mountains and Svartisen glacier, which form a natural border with the Salten district. In the south, Helgeland borders Trøndelag county.