Asos is banning products which contain feathers, silk, cashmere and mohair from its website.
The fashion retailer says it has updated its animal welfare policy and will stop stocking products using these materials by the end of January 2019.
Animal rights group Peta said it "applauds ASOS for leading the charge for compassion in fashion".
Asos has already banned fur, angora and other rabbit hair and products which use materials from vulnerable animals.
What are these products?
- Mohair is a fibre used in clothing such as sweaters, hats and other fluffy accessories and comes from angora goats
- Cashmere is the hair taken from the undercoat of a cashmere goat
- Silk is the fibre that silkworms weave to make cocoons
- Down feathers are the feathers which are typically closer to a bird's skin
Under the updated policy, products containing silk, feathers and down, bone, teeth or shell (including mother-of-pearl), cashmere and mohair will no longer be stocked by Asos.
Peta claims that the mohair, cashmere, down and silk industries "exploit countless goats, geese, ducks, and silkworms, causing these sentient beings unnecessary pain and suffering".
Last month, the animal rights group released a video which it claimed showed "a groundbreaking expose of cruelty in the mohair industry".
It said the footage from an angora goat farm in South Africa showed workers "dragging, throwing, and even cutting the throats of fully conscious animals".
Brands including Topshop, Gap, Zara, Boohoo and Primark have all pledged to stop using mohair.
The move has mainly gone down well with people on social media.
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Newsbeat headed out onto the high street to get the reaction of shoppers too.
Thomas, 33, said he was "delighted" by Asos' decision and that "anything that discourages the hurting or harming of any animal is good".
But he admitted he was confused by the decision to no longer stock silk.
"They're insects, I don't think silkworms are going to notice. I think sentient animals definitely, but things like worms - it's not going to be such a big deal is it?"
Natasha, who was out shopping for shoes, said she's "not particularly" against buying animal products but doesn't think there's much point as there are enough fake alternatives available.
It's been suggested brands are responding to consumer demands for clothing that is considered to be more ethical.
However, animal products - such as fur - still make regular appearances in many high fashion shows and supporters argue it is more environmentally-friendly than synthetic alternatives.
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