To achieve this, it discharges four main functions; 1. responsible for the formulation and implementation of monetary policy, 2. ensure financial system development and stability, 3. ensure the payment system remain efficient, and 4. provide a banking role to the Government.

The Commonwealth Bank established many branches across Papua New Guinea including Port Moresby, Boroko, Rabaul, Lae, Wau, Bulolo, Goroka, Kavieng, Madang, Mount Hagen, Kundiawa, Popondetta and Wewak.

On Bougainville there was Kieta, Panguna, Arawa and early on a part-time sub branch at Loloho.

The bank maintained those facilities to support trade, local business, government and small savers.

The BNSW suspended its operations in Papua in 1941 after the Japanese Army captured many of the towns in which it had branches and agencies, and bombed Port Moresby.

BSP conducted public offerings in 1980 and 1981, resulting in local citizens holding 13% of the bank's shares.

In 1993, National Investment Holdings Limited (NIHL) first acquired NAB's 87% shareholding, and then the 13% of the shares in the hands of the public, giving it 100% ownership of BSP.

In 2013, BPNG made a Maya Declaration Commitment[10] to create an enabling environment for building an inclusive financial sector in Papua New Guinea.

Its objective is to ensure that individuals or groups for personal or professional gain do not abuse PNG’s financial system.