Now, Mrs Steenkamp hopes sharing what her daughter went through will help other women speak up, or ask questions of their friends and family to try to prevent domestic violence.
"I hope to save some young women and their children, that's the plan. Like I said, we can't just not get involved, it's something that I have to do now."
She is the guest speaker at the 25th anniversary dinner for Shine, the country's largest domestic violence prevention charity.
She said the "shocking" statistics around domestic violence in New Zealand - police receive a phone call every six minutes from a domestic violence incident - need to spur people to action.
"I think that we all have to take stock of our involvement in this thing. It's not going to go away, its escalating all over the world," Mrs Steenkamp said.
She is also in Auckland to learn from Shine, who have been operating at the coal-face for 25 years, and take the knowledge back home to South Africa.
Her message to young women: "If you realise you're getting in too deep, and it's the wrong person and they're abusive and controlling, you must try to get away."
Mrs Steenkamp said the stone-faced exterior during the trial was a "coping mechanism" and she would go home after sitting in court and break down.
"I felt so vulnerable in front of people," she said.
Mrs Steenkamp has never accepted Pistorius' version of events, and believes Reeva was leaving him that night when he fired four bullets through a bathroom door.
He told the court he believed an intruder had climbed in to his apartment and was locked in the toilet.
Instead, it was Reeva on the other side of the door. She was shot and fatally wounded.
Mrs Steenkamp said she remembers receiving the news of Reeva's death.
"I couldn't believe that she was killed in that horrendous way. It was barbaric. It was so avoidable.
"We're not living in the Dark Ages, we can speak about these things now."
The prosecution in the case has been granted leave to appeal the judge's decision at the Supreme Court of South Africa and seek a murder conviction.
Mrs Steenkamp won't be back in court to see whether the appeal is successful, and has detached herself from the legal proceedings.
"It's got nothing to do with me, it's the law."
Mrs Steenkamp will be speaking at the fundraising dinner, The Light at the End of the Tunnel, on Saturday night at the Heritage Hotel in Auckland.
How to get help
If you or someone you know is affected by domestic abuse call Shine's national helpline on 0508 744 633 (9am to 11pm, 7 days a week) or visit the website.