The Indian president has approved a giant programme to provide subsidised food to two-thirds of the population.
Pranab Mukherjee signed into law the food security ordinance approved by the cabinet two days ago.
Under the new law, the government will provide 5kg of cheap grain every month to nearly 800 million poor people.
The ordinance still has to be ratified by the parliament within six weeks of its first sitting, otherwise it will lapse, authorities say.
Opposition parties have criticised the government for passing the measure as an ordinance, after failing to win parliamentary support.
Critics say the plan is a political move to win votes and will drain India's finances. Supporters say it will help reduce poverty.
The ambitious National Food Security Bill, which will cost 1.3 trillion rupees ($23.9bn; £15.8bn) a year, is being called one of the world's largest welfare schemes.
It was an election promise made by the ruling Congress party and its implementation is expected to help the party in general elections due next year.
But the scheme is intended to combat hunger - despite impressive economic growth in recent years, India still struggles to feed its population and has more malnourished children than any other country in the world.
The bill proposes to provide a kilo of rice at three rupees (six cents; four pence), wheat at two rupees and millet at one rupee.
The measure will apply to 75% of Indians living in rural areas and 50% of the urban population.