The age of Mount St John is currently unknown but is older than 28,500 years old as the scoria cone is mantled in ash from Te Tatua-a-Riukiuta volcano.

[2][4] Mount St John is now known to be the source of the long lava flow that ran west down an old stream valley and out into the Waitematā Harbour as Meola Reef.

[6] The maunga is a place of great cultural and archaeological significance,[2] and was the site of a pā, and has retained Māori earthworks from that era such as kumara pits and terracing for housing.

[4] During World War II, an anti-aircraft artillery was built on Mount Saint John, in order to protect the city of Auckland.

The legislation specified that the land be held in trust "for the common benefit of Ngā Mana Whenua o Tāmaki Makaurau and the other people of Auckland".