The media regulator estimates that approximately 14 million people watch online pornography in the UK.
But it is so readily available that campaign groups have raised concerns that children see it at a young age – with one in 10 children seeing it by age nine, according to a survey by the Children’s Commissioner.
“As age checks start to roll out in the coming months, adults will start to notice a difference in how they access certain online services,” said Dame Melanie.
The rules also require services which publish their own pornographic content – including with generative AI tools – to begin introducing age checks immediately.
Age verification platform Yoti called such technology “essential” for creating safe spaces online.
“It is important that age assurance is enforced across pornographic sites of all sizes, creating a level playing field, and providing age-appropriate access for adults,” said chief regulatory and policy officer Julie Dawson.
However Aylo, parent company of the website Pornhub, told the BBC this sort of age verification was “ineffective, haphazard and dangerous”.
It claimed pornography use changed significantly in US state Louisiana after similar age verification controls came into force, with its website’s traffic dropping 80% in the state.
“These people did not stop looking for porn, they just migrated to darker corners of the internet that don’t ask users to verify age,” it claimed.
“In practice, the laws have just made the internet more dangerous for adults and children.”