Pet shops are to be banned from selling kittens and puppies in a Government move aimed at stopping puppy farming.
Third party sales of a cat or dog less than six months old will be prohibited.
This means buyers must deal directly with either the breeder or an authorised centre finding animals new homes.
Animal welfare minister David Rutley announced the ban on Sunday.
He said: "I urge anyone who is thinking of buying a puppy, or any pet, at this time of year to pause and think carefully before doing so.
"Pets become a part of our families and it is a decision that requires careful consideration and planning. It should not be undertaken on a whim or as a surprise.
"That is why we promote responsible pet ownership in our welfare codes and I urge fellow animal lovers to consider the idea of rehoming a dog from the many wonderful organisations across the country."
The move, announced by the The Department of Environment Food and Rural Affairs, followed a public consultation which found that there was 95% public support for such a ban.
Earlier this year a petition backing the Lucy's Law campaign, for a halt to sales by third-party commercial dealers, was signed by 150,000 people.
Defra said the ban, which will be introduced "when parliamentary time allows" in 2019.
It aims to make it harder for "high volume, low welfare breeders" to operate.
It also comes after new laws came into force on October 1, banning licensed sellers from dealing in puppies and kittens less than eight weeks old.
Earlier this year a petition backing the Lucy's Law campaign for a halt to sales by third-party commercial dealers was
Marc Abraham, TV vet, and founder of PupAid and the Lucy's Law campaign to ban third party puppy and kitten sales, said the announcement was "a real victory for grassroots campaigners as well as the UK's dogs and cats".
He added: "The third party trade supports and sustains both legal and illegal puppy dealing, inappropriate activities suffering exactly the same negative welfare implications; effectively the puppy or kitten (and their mum) is damaged before reaching the licensed or unlicensed seller.”
Other animal welfare organisations have also welcomed the move.
Battersea's chief executive, Claire Horton, said: "Properly enforced, this will help put an end to dogs being used as breeding machines and kept in shocking conditions.
"The days of unscrupulous puppy dealers lining their pockets with no regard for animal welfare must now come to an end."
While the RSPCA's deputy chief executive, Chris Wainwright, added: "We believe that cracking down on unscrupulous traders, who put profit ahead of animal welfare, will provide much-needed protection for prospective pet owners and animals.
"We have always said that an end to third party sales alone would not be enough to end the puppy trade crisis and we are pleased that this is being looked at alongside enhanced licensing conditions for breeders introduced earlier this year."
