"Oranga Tamariki know which children are at risk. Tūhoe's knowledge of whakapapa and our families means that we can provide insights into wider whānau and hapū connections," he said.
"Neither of us want a never-ending treadmill of state care."
Children's Minister Tracey Martin was at the signing and said there were numerous issues Oranga Tamariki could not change without community support.
"It's about more than just, 'Is that child safe?' It's also about what has created that need for protection for the child, what are the other things between us that we can provide," she said.
Oranga Tamariki reported 7500 children in their care and protection last year.
Whānau Ora Commissioning Agency Merepeka Raukawa-Tait this week spoke of rising concern in Māoridom about the Ministry.
"The time has come for change and a solution that is for Māori, by Māori, with Māori given the escalating disquiet in this country by our people," she said.
That came at the release of the terms of reference of a Māori-led inquiry into Oranga Tamariki.
It is one of four separate probes into the Ministry started since the release of a video of an attempted uplift of a six-day-old baby in May, including investigations by the Children's Commissioner, the Ombudsman and an internal review by Oranga Tamariki.
King Tūheitia on Wednesday addressed the issue while speaking at Tūrangawaewae Marae during his annual coronation event - but called for blame to not be put on the Government.
"My challenge is to the whānau, hapū, iwi to take care of our tamariki and where the need arises to place them in a safe home," he said.
"We must avoid blaming the Government and instead work on a solution. We have a chance to design a solution on our own."
Martin said the Ministry had years ago committed to Māori-driven solutions.
"I don't agree that the noise is getting bigger," she said.