KiwiBank Limited is a wholly owned subsidiary of the state-owned enterprise New Zealand Post Limited. Through KiwiBank, New Zealand Post provides banking services through its PostShops (post offices) and joint venture Books & More outlets around New Zealand. Hence KiwiBank has the most extensive network of branches out of all banks operating in New Zealand.

KiwiBank started claiming to offer low-cost banking to those apparently not served well by the existing, mostly Australian-owned, banks. KiwiBank advertised itself as New Zealand-owned, with a larger branch network than any other bank. Initially offering low-cost banking only to individuals, KiwiBank has introduced business banking progressively through 2005.

Banking only to individuals was a significant field of controversy in the bank's early days, as it excluded small and medium sized enterprises (SMEs). These small businesses form the backbone of the economies of most developed countries.

The bank was initiated as part of Alliance Party policy in the 1999-2002 Labour-Alliance coalition government. Many politicians were critical of the decision to set up KiwiBank and it was widely predicted KiwiBank could never be profitable.

In September 2005, the fledgling bank surprised some critics by posting a maiden full year profit of $7.2 million. Though most of the banks profitable revenue came from over the counter financial services (such as bill paying) that were pre-exisiting services offered by NZ Post before the establishment of KiwiBank.

KiwiBank has topped customer satisfaction surveys, matching TSB Bank, another New Zealand (though not state) owned bank.

Some people do not like the idea of KiwiBank, saying that their rates are not as low as the could be and take money away from common New Zealanders. The difference about KiwiBank is that this money now goes to the Government instead of off-shore.