The suburbs line the north-east coast of the city along the shore of the Hauraki Gulf and Rangitoto Channel.

[11] In the south, the mouth of the Wairau Creek forms the border between Castor Bay and Milford.

[12] The East Coast Bays are primarily formed from Waitemata Group sandstone, which accumulated on the sea floor during the early Miocene era, between 22 and 16 million years ago, and uplifted due to tectonic forces.

[14] Prior to human settlement, the inland East Coast Bays area was primarily a northern broadleaf podocarp forest, dominated by kauri, tōtara, mataī, miro, kauri and kahikatea trees.

[15][16] By the 19th century, the area was primarily scrubland, vegetated by plants such as mānuka, tutu and harakeke flax.

[21][22] The North Shore was settled by Tāmaki Māori, including people descended from the Tainui migratory canoe and ancestors of figures such as Taikehu and Peretū.

[23] During his arrival in New Zealand, Hoturoa, captain of the Tainui, guided the waka to the Waiake Lagoon (Deep Creek), which was a safe anchorage for the canoe.

[24] Many of the early Tāmaki Māori people of the North Shore identified as Ngā Oho.

[14] The warrior Maki migrated from the Kāwhia Harbour to his ancestral home in the Auckland Region, likely sometime in the 17th century.

[32][27] By the 18th century, the Marutūāhu iwi Ngāti Paoa had expanded their influence to include the islands of the Hauraki Gulf and the North Shore.

[34] The earliest contact with Europeans began in the late 18th century, which caused many Tāmaki Māori to die of rewharewha, respiratory diseases.

[16] In 1841, the Crown purchased the Mahurangi and Omaha blocks; an area that spanned from Takapuna to Te Ārai.

[14] Visitors primarily arrived by steam ships,[48] and the southern East Coast Bays area began to develop after the Milford to Bayswater tram improved access.

[49][14] During World War II, the coast from Torbay south was fortified with defenses, including pillboxes along the coastline and hills, and barbed wire ditches.

[50] After the end of World War II, local residents lobbied for the creation of an East Coast Bays borough, separate from Waitemata County.

[53] Between 1971 and 1975, East Coast Bays was the fastest growing area of Auckland, seeing a population increase of 47.3%.

In 1974 the county was dissolved,[73] and Long Bay became a rural area incorporated into Takapuna City.

East Coast Bays is also the name of an electorate from which an MP is elected to serve in the New Zealand Parliament, which first formed in 1972.