During the bootcamp rounds of the U.K. series, on 23 July, 2010, Harry Styles, Liam Payne, Louis Tomlinson, Niall Horan, and Zayn Malik were put together as a group, and went on to reach the finale of the contest.
They became international superstars and remained a five-piece until 2016 when Malik quit to go solo. The remaining bandmates then announced a hiatus, which has been in place since the beginning of 2017 - with no signs of ending.
Despite fans' hopes of a 10th anniversary reunion, Niall, Harry, Liam, and Louis remain committed to solo careers, but they took time out on Thursday (23Jul20) to jump on social media and acknowledge their anniversary.
Posting a shot of himself and his four bandmates on Twitter, Style wrote, "I've been struggling to put into words how grateful I am for everything that's happened over the last ten years. I've seen things and places that I'd only ever dreamt of when I was growing up."
"I've had the pleasure of meeting and working with some of the most incredible people, and gained friendships that I know I will treasure for the rest of my life. None of this would be possible without the support you've given along the way. And for that, I will be forever thankful. I just can't believe it's been ten years. Thank you to our crew, our team, and everyone else who helped us along the way. To all the fans, I love you, and I thank you with all my heart. You did it all, and you changed everything."
"And finally... to the boys," he added. "I love you so much, and I couldn't be prouder of everything we achieved together. Here's to ten."
Horan added, "When I met these four gents there was no way I thought we would go on to do what we did. So many unbelievable memories we shared together. We felt the adoration of millions from around the planet on a daily basis and it was mind blowing."
"It's such a major part of our lives and always will be. Cheers to US today boys and thank you to all you beautiful people who have supported us over the last 10 years."
Tomlinson also jumped on Twitter to mark the occasion, writing, "Too many incredible memories to mention but not a day goes by that I don't think about how amazing it was. @NiallOfficial @Harry_Styles @LiamPayne @zaynmalik. So proud of you all individually."
And Liam Payne added a screenshot of a text he sent his father on the day One Direction formed, which featured the first photo of the group and read "Im in a band (sic)."
He wrote, "What a journey... I had no idea what we were in for when I sent this text to my Dad ten years ago at this exact time the band was formed. Thanks to everyone that’s supported us over the years and thanks to the boys for sharing this with me #10YearsOfOneDirection."
One Direction have also released a special five-minute video documenting their time together, featuring behind-the-scenes footage from their music promos and tours.