Harry Styles, Niall Horan, Liam Payne, Louis Tomlinson and Zayn Malik were put together as a five-piece during The X Factor Boot Camp stage back on July 23, 2010.
The group celebrated their two-year anniversary as a collective by thanking their fans for all of their support.
"Guys its been 2 years today since we were formed, its been incredible so far, its all down to you guys! Love you all soo much ! Thank you," Horan tweeted.
Malik added: "Wow 2years, what an amazing journey and its all down to you guys. Thank you, sending my love to you all #2yearsof1d"
The past two years have seen One Direction finish third on The X Factor in 2010, have an international number one single ('What Makes You Beautiful') and album (Up All Night) and embark on a world tour.
Copyright: WENNThe group have dominated social media and the web, becoming a YouTube phenomenon. Their three official music videos have a combined total of over 350 million views.
One Direction are currently creating their second studio album and have worked with McFly and Boyce Avenue on tracks for the new collection.
Watch the music video for One Direction's 'What Makes You Beautiful' below: