"I was a cop for 18 years and in those days, we were trained in the ideology that the freedom liberation movements were considered the enemy," Mr Steyn said.
Four years before Mandela became president, Steyn said, he "didn't believe any of the stuff" the man affectionately known as Madiba was saying.
"I thought all that reconciliatory talk was just a facade," and viewed Mandela as an opportunistic politician, "saying things that are expedient at the time".
It was only when he engaged with the former President in person that he found Mandela's motives were genuine.
Mr Steyn also served as the security liaison for the All Blacks during the 1995 Rugby World Cup and has recently returned home to Johannesburg from Brazil, where he was a private security consultant at the Fifa World Cup.
TEDx organiser Elliot Blade said he was excited to hear Mr Steyn's journey, along with the stories of other guest speakers. "It's awesome Rory decided to come down here to us with such a unique and empowering story."
Mr Blade launched the conference to showcase inspirational New Zealanders in the popular international TEDx event format. TED stands for technology, entertainment and design. The "x" indicates an independently organised event.
"We wanted to share with Kiwis some of the great stuff they're doing in our country," he said.
tedxauckland.com
Speakers at TEDx
Saturday, August 16, Aotea Centre, Auckland:
Vaughan Rowsell - founder of Vend cloud software
Mike Allsop - Air New Zealand pilot, Everest mountaineer, adventurer and extreme marathon competitor
Rebecca Mills - sustainability strategist
Urzila Carlson - comedian
Rachel Callander - award-winning photographer
Catherine Bell - Dish magazine co-founder
John Boone - interactive percussionist