The website, created in Mark Zuckerberg's college dorm, reached the milestone this morning.
Since its launch in February 2004, Facebook has hosted 1.13 trillion 'Likes' of content on its network, including pages, status updates, brands, products and pictures.
There have been 140.3bn friend connections and 17bn check-ins at locations, while 219bn images have been shared by Facebook users.
More than 300 million new photos are uploaded every day to Facebook, and 62.6m songs have been played on the network 22bn times since 2004, which equates to 210,000 years of music.
Mark Zuckerberg, the chief executive of Facebook, said in a statement: "This morning, there are more than 1bn people using Facebook actively each month.
"If you're reading this: thank you for giving me and my little team the honour of serving you. Helping a billion people connect is amazing, humbling and by far the thing I am most proud of in my life.
"I am committed to working every day to make Facebook better for you, and hopefully together one day we will be able to connect the rest of the world too."
Over its short history, Facebook's tempestuous foundation has formed the basis of Hollywood movie The Social Network.
In May this year, the firm also became the only ever US company to debut on the stock market with a valuation of more than $100bn (£62bn).
That valuation has since almost halved following a major slump in the share price due to investor unease over Facebook's long-term prospects.
Facebook launched as a desktop service but now almost half of its users access their profiles on smartphones and tablets - and Facebook has been accused of being slow to respond to this shift.
However, the network has been busy using the $16bn it generated from the initial public offering (IPO) to build its business, with steps including the acquisition of photo-sharing app Instagram and making efforts to unlock new revenue streams, such as the Facebook Gifts service and the Promoted Posts initiative currently in testing.
As well as providing a place for users to socialise online, Facebook has also spawned a new generation of digital businesses that use the network to reach their customers.
Alex Dale, from casual games maker King.com, said: "King.com started out on Facebook last year and we now generate over 3bn game plays every month.
"We recently launched one of our top games, Bubble Witch Saga, on mobile. We can see already that the most engaged players are those that connect with Facebook Connect to play the game, synchronising their scores and progress across web and mobile.
"One billion people with social connections on Facebook provides an incredible opportunity for developers."
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Charity JustGiving, which uses Facebook to generate more donations and awareness, added: "JustGiving turns Facebook users into powerful advocates for their chosen cause, spreading generosity across the web.
"Currently, each 'like' of a JustGiving page on Facebook generates an average of £5 in donations to charity. So if every single one of Facebook's 1bn users across the world were to 'like', or share, a charity campaign once a day - in just a few days they could raise sums comparable to the total amount raised for the Haiti earthquakes or in the aftermath of Hurricane Katrina."
Reaching 1bn members worldwide is a great achievement for Facebook, but the firm has faced criticism previously over its perceived intrusion into the privacy of its users.
As the social network seeks to build a multi-billion-dollar-generating business from its massive user base, these controversies and headlines are unlikely to go anywhere soon.