"As we mark six months since the horrific events of March 15, we remember the remarkable community spirit and unity that was on display in the weeks that followed," she said.
"But we also acknowledge we will be dealing with the trauma of that day for years to come."
Ardern praised Canterbury District Health Board (CDHB) for its "incredible job" from the emergency response treating victims, through to supporting their physical and mental recovery.
But she stressed that there is more work to be done.
"It's vital that survivors, families, the Muslim community and the people of Christchurch know that we will be there to support them for the long-haul," Ardern said.
The additional funding will enable ongoing and meaningful support, including:
• Treatment for post-traumatic stress disorder and other serious issues.
• Community mental health and addiction support.
• Cultural competency training for GPs.
• Allowing extended GP consultations for those directly affected by the attacks.
• Building community resilience.
The Prime Minister thanked everyone involved in supporting people affected by the terror attacks – from community leaders and organisations to medical and mental health staff.
"Your efforts have made a huge difference in the most challenging of times," she said.
"Today's announcement means our mental health services can continue to deliver the support that is needed now and into the future."