The town is located approximately 17 kilometres north of central Christchurch, close to the mouth of the Waimakariri River.

Kaiapoi suffered extensive damage in the 2010 Canterbury and also the February 2011 Christchurch earthquakes, which rendered many homes uninhabitable and businesses inoperable.

This patch of land between the north and south branches of the Waimakariri was the largest island in the lower reaches of the river.

[4] When the Christchurch settlement was planned, a secondary market town named 'Mandeville' was proposed by Captain Joseph Thomas to support north-Canterbury farmers.

He was concerned that the Canterbury Association had not made enough progress in establishing the promised Anglican model values in their new settlements.

Tancred wrote to Henry Sewell, asking him to instruct John Robert Godley to set aside land for the Gladstone settlers.

By this stage in 1852 the Canterbury Association was not performing well financially, and was soon to wind-up and hand control to the newly-formed provincial government.

An offer of 50 acres (20 ha) of church land was made and agreed to, but the settlers had additional demands that could not be immediately met.

[11] However, the suitability of the site was so great that Sewell began the work of establishing the town anyway, but rather under the direction of the Canterbury Association and not the Gladstone settlers.

[15] Kaiapoi was an important hub for the early north Canterbury settlers, largely due to the river port that was established there.

The mouth bar of the Waimakariri River posed a significant hazard to ships, and many ran aground.

During the great storm of 1868 the Waimakariri flooded, destroying buildings, bridges, telegraph lines and port facilities.

Local businessman John Sims purchased coastal shipping vessels and expanded the wharf facilities at Kaiapoi during the 1870s and 80s.

This business produced high-quality woollen blankets and clothing, and was successful during the 1880s in spite of the wider economic recession.

[23] The facility processed sheep from across North Canterbury and remained an economic centre of the town until its closure in 1991.

[24] During the 1918 influenza pandemic seventeen people died of the disease, meaning that Kaiapoi had the second-highest death rate in North Canterbury, after Amberley.

[28] Changes upstream of the town had the effect of reducing the flow of the North Branch of the river, and making it less prone to flooding.

[39] Kaiapoi is defined by Statistics New Zealand as a medium urban area and covers 14.65 km2 (5.66 sq mi).

It, however, has survived and prospered, and although there is some local industry, a large percentage of the population works in the neighbouring city of Christchurch.

Outdoor recreation options include the Kaiapoi River which is deep enough for boating, with multiple accessible boat-ramps.

[60] The nearby Waimakariri River Regional Park is popular for kayaking, fishing, cycling and off-roading.

The Waimakariri District Council operates several public recreation facilities in Kaiapoi including a library,[61] museum,[62] and a swimming pool.

Prior to the completion of the motorway in December 1970,[71] State Highway 1 ran down the main street of Kaiapoi.