More than 60 million people are watching the BBC iPlayer for free outside of the UK by masking their location, according to a new report.
Analysts estimate 65 million people regularly access the BBC catch-up TV service using virtual private networks (VPNs) or proxy servers.
In China alone that figure is thought to be around 38.5 million.
The iPlayer is meant for UK TV viewers only and is funded by the licence fee. A global iPlayer was closed last month.
The report from GlobalWebIndex said that despite VPNs being thought of as "fairly niche tools which are the preserve of the tech-savviest individuals", around 25% of internet users worldwide now use them, primarily to access better entertainment content.
The research company surveyed more than 45,000 internet users across 34 countries, including China, the US, France, Germany, Ireland, India and Brazil.
It found that while the iPlayer is "geo-restricted to be viewable only by people resident in the country", the BBC service does in fact have "a huge global audience".
"The implications for iPlayer are stark," said Jason Mander, head of trends at GlobalWebIndex, writing in the report.
"However, rather than seeing this as a threat, there's much good news here for the BBC."
The report highlighted that 75% of the 65 million already pay for subscription services like Netflix or Hulu, so there was "clear potential" for the BBC to create "new revenue streams".
"If even a relatively small proportion users could be converted into paid users, the additional revenue it could create for the BBC would be significant."
A global iPlayer subscription service, which allowed viewers in Europe, Australia and Canada to watch programmes like Doctor Who, was shut down last month.
GlobalWebIndex also found the domestic iPlayer to be the most popular on-demand service in the UK by far - with 45% of internet users aged 16-64 accessing it in the past month, and just 4% being unaware of the service.
Netflix is the second most popular service, attracting 24% of web users.
The BBC's most recent iPlayer figures revealed there were 222 million requests for TV programmes in May, with Peter Kay's Car Share the most popular show.
The GlobalWebIndex figures would suggest that 29% of these requests may have come from TV viewers outside of the UK.