Environment Secretary Michael Gove published a draft Bill requiring law-makers to recognise animals as conscious beings who can feel pain.
The legislation raises from six months to five years the maximum jail term for cruelty to animals in England and Wales.
It also explicitly rejects the welfare exemptions that EU law allows for “cultural” but cruel practices such as bullfighting and producing foie gras.
David Bowles, of the RSPCA, said: “This is potentially great news for animals post-Brexit.”
Claire Horton, of London’s Battersea Cats and Dogs Home, said: “It will make a massive difference for animals and hopefully really start to act as a deterrent and put England back where it should be at the top of the league tables for animal welfare.”
Mr Gove said: “We are a nation of animal lovers.
“So we will make Brexit work not just for citizens but for the animals we love and cherish too. Britain outside the EU can have higher standards on the environment and indeed on animal welfare.”
Meanwhile, ministers are considering spending more overseas aid on cutting plastic pollution of the oceans.
It follows heightened public awareness highlighted by Sir David Attenborough’s BBC TV Blue Planet II series.
Mr Gove is said to have pressed the Department for International Development to do more after research showed 90 per cent of plastic entering the planet’s seas comes from just 10 rivers in Asia and Africa.