The micro-blogging website has now overtaken the amount of people who buy daily national newspapers in the UK, which stands at 9,002,963, reports The Guardian.
Studies suggest that the UK is now only behind the US, Brazil and Japan in terms of active Twitter nations.
Twitter states that 60% of its users actively use the site by either tweeting or uploading pictures and videos, while YouTube only sees 1% of its users actually upload content.
The report also reveals that 80% of British Twitter users who have logged onto the site over the past month did so on a mobile device, while the global average is just 55%.
A Twitter UK spokeswoman said: "We have seen growth in the number of people signing up from a mobile."
The company will mark its one-year anniversary of operating with a UK office on June 1. It currently employs 30 members of staff.
Stephen Fry, Jessie J, One Direction and Ricky Gervais are among the UK's biggest celebrity Twitter users.
Twitter was recently suggested to be more addictive than chocolate or cigarettes.