One Direction was formed by Simon Cowell on The X Factor in 2010. Malik left the group in 2015, and the remaining members went their separate ways shortly thereafter.
"I’ve been struggling to put into words how grateful I am for everything that’s happened over the last ten years," Styles wrote on Instagram alongside a pic of the band hugging. "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," he continued of the fans. "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."
Styles ended his sweet note with a message "to the boys."
"I love you so much, and I couldn’t be prouder of everything we achieved together," he wrote. "Here’s to ten."
Meanwhile, Payne celebrated by posting a pic of a text he sent to his dad the day One Direction was formed. "I'm in a boyband," the text read.
"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," he wrote. "Thanks to everyone that’s supported us over the years and thanks to the boys for sharing this with me #10YearsOfOneDirection"
Horan shared a throwback pic with the band onstage, along with a sweet message, to mark the day.
"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," he marveled. "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," Horan added.
Tomlinson shared an epic photo of the group, which, he revealed, was actually the first pic they ever took together.
"The memories we've shared together have been incredible," he gushed. "Can't believe its been 10 years already. I look back incredibly proud. Thanks for everything lads and love to you the fans as always."
The band itself celebrated reaching the 10-year mark by posting a new video that featured footage from each of its eras. From appearing on TheX Factor in 2010 to the adventures that came with releasing five albums in five years.
Back in April, a source told ET, "The guys started talking more frequently recently and have worked on putting a lot of things behind them," adding that they wanted "to do something for their fans" in honor of the 10-year anniversary.