All Government policies will have to pass a "family friendly" test under plans set out by David Cameron.
The Prime Minister insisted families are crucial for society, and should be at the heart of everything politicians do.
From October their interests will become an explicit element of Whitehall impact assessments alongside issues such as cost-effectiveness, equality and the environment.
Mr Cameron said the Coalition had already been prioritising families, but the move would "formalise" the process. He highlighted a doubling of funding for relationship counselling through Relate to £19.5 million.
"When we ask ourselves the question 'who is it who brings up children, cares for the elderly, helps us when we're sick, inculcates the right values and teaches people?', the family does all of those things for us," he told BBC Breakfast.
"I think a lot of politicians have shied away from talking about relationships – not surprisingly, we're not perfect ourselves and also no-one wants to be accused of being judgmental.
"But when we contemplate the fact that family and relationship breakdown has enormous consequences for our society and for our children, I just think it is worthwhile talking about and acting on these things and, for instance, properly funding relationship support through organisations like Relate which this Government, under my leadership, has done and will continue to do. Of course there are some cases where it is better for parents to split up and I wouldn't for one minute want to stop that.
"But where you can help people come together and stay together then surely the Government should play its part in helping?"
Mr Cameron stressed that single parents are not being left out of the Government's priorities.
"Single parents do an absolutely brilliant job bringing up children. And of course we help them through the tax and benefit systems and in lots of other ways," he said.
In a speech later, the premier will hail figures showing a 25 per cent rise in adoptions, an area he has personally championed.
"The reality is that in the past the family just hasn't been central to the way government thinks. So you get a whole load of policy decisions which take no account of the family and sometimes make these things worse.
The intervention comes as the Government prepares to launch a major extension of its programme to tackle troubled families – set up by Mr Cameron in the wake of the riots in London and other English cities in 2011.
Up to 500,000 are due to be targeted – more than four times the number targeted in the initial stage – with work due to begin first in the 50 local authorities which have so far proved most successful with the work.