Free school meals for six and seven-year-old children will go ahead from this September, Nick Clegg assured Good Morning Britain.
The Deputy Prime Minister said his flagship policy was "properly budgeted" and had the backing of both the Education Secretary and the Minister for Schools.
"I think it is going to be one of the most positive things that has happened in our school system for a long time. Of course there are lots and lots of schools across the country - we are helping them but it will happen in September and it will be of great benefit."
The Chancellor has announced that financial resources will be provided to fund expansion of free school meals to all school children in reception, year one and year two.
Free school meals have lead to "healthy children and ultimately a better performance at school," said the head of a north London primary.
Headteacher at St Mark's primary school, Calvin Henry, readily supported free school meals for infants and had already implemented the policy at his school.
Free school meals for infants will not be funded by taxing the poor, the minister for schools has told Daybreak.
Liberal Democrat David Laws was adamant the £1 billion giveaway would be funded by closing tax loopholes which would "ensure policies such as this can be progressive".
The Chancellor will announce full funding details of the free school meals policy later this year in the Autumn Statement, Mr Laws added.
Concerns are being raised about the Government's ability to afford a £1 billion giveaway handing all children under eight free school meals alongside a likely tax break for married couples.
Deputy Prime Minister Nick Clegg announced the £600 million school meals scheme under a deal with the Conservatives to allow them to press ahead with a tax break for married couples that is widely expected to cost around £500 million.
A Treasury spokesman said any plans for more spending or cuts "would be taken forward in the Autumn Statement".
Attacking the scheme, the Taxpayers' Alliance described it as a "conference gimmick" while the Institute of Economic Affairs said it was "an enormously bad use of public money".
Every child at infant school in England will receive a free school meal from next September, Nick Clegg announced today.Read the full story ›
Following the Government's announcement that every child at infant school in England will receive a free school meal from next September, ITV News viewers have been giving their views on social media:
All children should get free school dinners until they are 18 unless the parents opt out.
Good nutrition, table manners, and the social side of eating a meal together is missed in many households these days and should be part of education, not a profit making business.
Why do we want kids fed at school? The meals are of poor quality, nutritionally poor and another step to the state taking over from parents.
I would love to see all school children get a good balanced meal. It's been proven that it helps with the learning process (amongst other things).
And if it's given to all children then there is no distinction between those who can afford it and those who can't.
Deputy Prime Minister Nick Clegg and his wife Miriam Gonzalez Durantez took a break from the Liberal Democrat conference in Glasgow to visit a primary school ahead of the Government announcement on free school meals today.
The Lib Dem leader announced a new £600 million scheme giving all infant school children in England a free school meal from September 2014.
The measure is aimed at helping financially-stretched families but will also have education and health benefits, Mr Clegg said.
The authors of the original School Food Plan which called for the introduction of free school meals have praised the Government for introducing free meals for infant school children in England.
Henry Dimbleby and John Vincent, who co-authored the Government-commissioned review into school meals, tweeted their pride at the new policy:
proud of our country tonight. Universal Free School meals for the first three years of primary school. #schoolfoodplan well done the govt
Universal free school meals for reception, year 1, and year 2. From next september. WOWSER. #schoolfood
Disadvantaged students at sixth form colleges and further education colleges in England will also be eligible for free school meals from next September.