CCTV is to become mandatory in all slaughterhouses in England, the Government has confirmed after a consultation showed overwhelming support for the move.
Britain's Environment Secretary Michael Gove said the new rules would "cement the UK's position as a global leader" on animal welfare standards.
The measures will give the UK's Food Standards Agency vets unfettered access to the past 90 days of footage to help them monitor and enforce the standards.
The announcement came after proposals were put out for consultation to industry, welfare groups and the public in August, with more than 99% of almost 4,000 respondents supportive of the plans.
Mr Gove said: "We have some of the highest animal welfare standards in the world and want to cement our status as a global leader by continuing to raise the bar.
"The reaction to this consultation highlights the strength of feeling among the public that all animals should be treated with the utmost respect at all stages of life and be subject to the highest possible welfare standards.
"These strong measures also provide a further demonstration to consumers around the world that as we leave the EU we continue to produce our food to the very highest standards."
Legislation will be introduced in the new year and come into effect in the spring, with all slaughterhouses required to comply following an adjustment period of up to six months.
Any breaches of welfare standards by a slaughterhouse can result in an enforcement notice, the suspending or revoking of staff licences or referral for a criminal investigation.
British Veterinary Association senior vice president Gudrun Ravetz said mandatory installation of CCTV was a "vital tool" for ensuring high standards of animal health, welfare and food safety in slaughterhouses.
"Official veterinarians carry out an essential role in slaughterhouses by independently assessing and reporting breaches of animal welfare, and unrestricted access to CCTV footage will allow them to carry out this role even more effectively."
Heather Hancock, chairman of the Food Standards Agency, said: "Last year, the FSA board concluded that, without mandatory CCTV in slaughterhouses, we would see minimal further progress in businesses improving animal welfare or complying with official controls to protect public health.
"We look forward to working with the industry as CCTV plans are implemented, and to seeing public confidence rise as a result."
The RSPCA's head of public affairs in the UK, David Bowles, said: "This is a very welcome and crucial step towards introducing higher welfare right across the food chain.
"We applaud the Secretary of State for his steadfast and focused commitment to ensuring the highest possible animal welfare standards in the UK once we have left the EU.
"The RSPCA looks forward to seeing the details of the proposal as issues such as where the cameras will be located, footage quality and storage, and who can have access to it are essential to making the legislation meaningful.
"We also believe there are further ways to improve the slaughter of farm animals once the UK exits the EU, such as prohibiting electrical waterbath stunning for poultry and prohibiting slaughter without stunning."