The service, available online and via apps for iPhone and Android, involves users 'stumbling' on new content rather than searching for specific items.
Users set up an account and state their selected interests, and then the StumbleUpon system finds and recommends web content and "hidden gems" that they might like.
Alongside suggesting web pages based on users' interests, the system also learns the tastes of people they choose to 'follow' and aggregates the most popular 'likes' of its 25m users.
The idea is that StumbleUpon will take its users "down interesting but often unexpected paths, bringing the possibility of surprise to every Stumble".
Any favourite Stumbles can be shared via email, Facebook, Twitter and other social networks, and the site also rewards users for each Stumble they make.
According to data from people in Britain already using the US version of StumbleUpon, male UK Stumblers are most interested in technology, photography and gadgets, while female Stumbles prefer books, fashion, magic and illusion.
However, British people overall are apparently less interested in information on sexual health, relationships and fitness than their US counterparts.
For the launch of its UK version, StumbleUpon has partnered with a range of UK entertainment brands, including Digital Spy publisher Hearst UK, IPC Media, The Week UK and Spotify, to offer a range of content more relevant to the British market.
"We think the premise of StumbleUpon - to connect users with the stuff on the web that matters to them - has universal appeal, and so we are excited to officially bring our brand of serendipitous discovery to the UK market," said Marc Leibowitz, the vice president of worldwide business development at StumbleUpon.
StumbleUpon has also announced the most popular links so far among its UK users, including:
- Floating football pitch video on YouTube video curation site Devour
- Why not buy a plot of land in the Scottish Highlands with Highland Titles?
- TechLand's rundown of the "50 Best iPhone Apps 2012"
- TED's feature on "100 Websites You Should Know and Use"
- And finally, Woman's Day's "10 Alarm Clocks That'll Get You out of Bed"
Watch a video below introducing StumbleUpon's approach to content discovery: