Harry and Caroline were both pictured at a book launch party for Lou Teasdale: The Craft, which was held in London's Shoreditch.
The 1D singer dressed down for the event and opted to wear black skinny jeans teamed with a 90s Calvin Klein sweatshirt and bandana.
Xtra Factor presenter Caroline, meanwhile, did glam up in a sheer varsity top, black leather trousers, a blazer and heels. The 34-year-old completed her look with a slick of red lipstick.
The pair began dating in October 2011 and their relationship caused controversy due their 14-year age difference.
However, following their split in January 2012, Caroline insisted that they had remained friends and had never planned to have a serious relationship.
Last September, Caroline told Metro: "It was just really fun to hang out… I don't think we were ever going to have a long-term future.
"It was fun and it was hurting nobody… [Breaking up] was fine. And now we're friends."
Couples who have split in 2014:
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