Ardern said women's refuges and other agencies dealing with violence had been "unfairly distracted and undermined" over the past decade.
The Salvation Army's Major Pam Waugh said the funding was a huge boost, though it would need to be sustained over a long period to make a difference.
"It is enough to get started and to make a huge impact," Waugh said.
"Family violence is one of the biggest problems in creating poverty, as well as the other issues, so we need to build on that."
About 70 per cent of the Salvation Army's clients had either been abused themselves or witnessed family violence.
"So we see children that are very stressed by it. We see children that become very marginalised.
"And we see family living in complete poverty where the financial stress of it becomes a huge problem for them."
Over the past decade, the organisation had dipped into its reserves to keep running.
"We've had to cut some services, we haven't been able to give good wage increases to our staff, we've had to actually lay staff off."
Among the services it had cut were financial mentoring, welfare support and social work.
Social Development Minister Carmel Sepuloni said frontline services would now be able to expand into areas where there was no support and address rising demand for services.
"Family violence has a damaging, yet often hidden, impact on victims' lives, including their ability to work and lead a normal life," Sepuloni said.
"This funding will provide a boost to around 150 providers of family violence services nationwide.
Jan Logie, Under-Secretary to the Minister of Justice, said the funding was an important first step for services which were stretched to "breaking point".
"As we start the broader work of challenging and responding to family and sexual violence, it's crucial that victims and their families can get the support they need now. They can't wait."
New Zealand has one the worst rates of family violence in the world. Police are called to an incident about every five minutes - around 110,000 cases a year. That is despite around 80 per cent of cases going unreported.