Viewers will have to confirm they have a TV licence before they can catch up on shows on BBC iPlayer when a loophole is closed on Thursday.
People had been able to watch BBC shows they had missed on live TV for free, but will now risk prosecution and a £1,000 fine if they download or watch programmes on iPlayer without a TV licence on any device.
Currently, only live content is covered by the £145.50-a-year licence fee and viewers must confirm they have paid before they can watch a live feed of BBC channels.
This policy is being extended to shows on the catch-up service.
It is unclear how the new rules will be enforced, as no plans to ask viewers to enter licence fee details on iPlayer have been revealed by the BBC.
Last year, the BBC announced a £150 million shortfall in licence fee income for 2016/17, saying there had been a faster-than-predicted fall in the percentage of households owning televisions because of people viewing through catch-up.
The Government committed to closing the loophole, with John Whittingdale, then culture secretary, saying in March: "The BBC works on the basis that all who watch it pay for it.
"Giving a free ride to those who enjoy Sherlock or Bake Off an hour, a day or a week after they are broadcast was never intended and is wrong."
The Government set out plans to update licence fee legislation, as part of negotiations which saw the corporation agreeing to cover the cost of free licences for the over-75s.
People who already have a TV licence will not be affected by the change and viewers will not need a TV licence to download or watch programmes on demand from other providers, such as YouTube, Netflix, ITV Hub, All 4 or Demand 5.
A BBC spokesman said: "When you click to play something on BBC iPlayer, it currently asks you to confirm you've got a TV licence if you're watching something live.
"From tomorrow, a pop-up will appear when you go to play something, asking you to select if you have a TV licence, as you'll need one to watch live, catch-up and on-demand programmes on iPlayer."
A TV Licensing spokesman said: "We know the vast majority of people are law abiding and would anticipate those who need a licence for the first time will buy one.
"We have a range of enforcement techniques which we use and these have already allowed us to prosecute people who watch on a range of devices, not just TVs."