Hackett was born in Pukekohe, growing up on Auckland's North Shore. He attended Westlake Boys High School.
He left school at the age of sixteen to serve an apprenticeship as a carpenter-joiner. During this time he took up snowboarding and skiing.
He moved to Perth where he sold encyclopaedias for four months, later returning to New Zealand to set up a construction business.
Inspired by the Vanuatu ritual called land diving, Hackett and fellow adventurer Chris Sigglekow, sought ways to make bungy jumping safe. Using a mathematical formula developed by New Zealand's Department of Scientific and Industrial Research, he created a super-stretchy elastic bungy cord in the mid-1980s.
He is currently working on “Skypark” in Sochi, a Russian adventure park that will include a multitude of activities including the world’s longest suspended public walkway.