Ms Dette said the nationwide march was creating a "massive amount of awareness.
"The stories are horrific, they are all real.
"If you do nothing, nothing changes."
She said the plea bargaining for Moko's killers should never have happened.
"His death was murder, when a child is tortured day after day.
"We need consequences for actions, we need tougher sentences, we need law reform.
"Enough is enough, this has to stop.
She said there is no more time for excuses and blame.
"It can't be blamed on your upbringing, your environment, the government.
"You, and only you, are responsible for your actions."
A minute's silence was observed at 10am, the time of sentencing for Moko's killers in the High Court in Rotorua for manslaughter.
Tania Shailer, 26, and David William Haerewa, 43, were sentenced to 17 years each, the highest sentence ever handed down in New Zealand for manslaughter of a child.
Carterton School youngsters led a haka for Moko, before balloons were released by all children.
Attending the march were Nelson and Noeline Tepu, parents of Bevan Tepu, who died in the Ratima massacre with six other members of his family 24 years ago this week.
Prominent throughout was a family contingent in remembrance to Gavin Glenn Rimene, who died at age five, 26 years ago, allegedly bashed by his caregiver.
His mother, Annabelle Rimene, said her family wanted to march to remember Gavin, putting together signs and printed hoodies to honour the Masterton youngster.
"The girls wanted to acknowledge him, as he was not acknowledged over the years.
"My niece had all these tops made."
Gavin's sister, Kiani Parkes, said it was time for New Zealand to "stand up".
"Children cannot change abuse - adults can.
"My little boy has always been on my mind."
After her speech was read out by her daughter, Ms Rimene told the crowd how she thought of her dead son every day.
"To this day his killer walks free among us. Today we make a stand for my sweet little boy and I believe we bring justice to him as we stand here and remember him."
Ms Rimene encouraged people who knew of child abuse to report it and for the perpetrators to seek help.
"Please, please, if you know something, stand up, say something. Tell someone, and they will get help for you. That's all I ask."
Masterton Mayor Lyn Patterson canceled her plans in Wellington and took part in the march.
"For me it's about the needless death of another child," she said. "Today is for New Zealand and our appalling record of child abuse."
Mrs Patterson said it was appalling to think there were people in New Zealand communities who "think they can treat children in such a despicable manner".
"Today is about our kids," she said.
Lyn Buckley and Michelle Cooper from Wairarapa Women's Refuge were behind the march, saying the laws needed to be changed.
"The perpetrators, they need to be held responsible," Ms Buckley said. "We're protesting against the system."
Ms Dette and Mrs Ritiki hugged at the end, their pride obvious in organising the march.
"We've never done anything like this before," said Ms Dette.
"It was huge for us."
A no-show at the march was Masterton's faction of the Right Wing Resistance, a white pride group, who had earlier wanted to show solidarity with marchers in the fight against child abuse.
Ms Dette would not comment on their absence, but said she was just happy there had been "no drama" for the march and everything went smoothly.
The RWR, including Masterton representative Vaughan Tocker, had received widespread criticism and abuse on social media at the idea of attending the march, despite organisers saying anyone was welcome to come.
Last week Race Relations Commissioner Susan Devoy published a letter in the Times-Age, condemning the Nazi appearance of the RWR members.
