The 23-year-old American actress was spotted backstage at Horan's X-Factor U.K. finale performance. The 22-year-old Irish singer and his bandmates, who got their start on the ITV reality competition, sang their new singles "Infinity" and "History."
Gomez and Horan later attended the show's after-party in London, but left the bash separately. The pair were romantically linked this month, but Gomez denied dating rumors to Entertainment Tonight at the Billboard Women in Music event Friday.
"Oh my God! No," she responded when asked if she and the singer are an item. "I love him, I always have. He's amazing."
The X-Factor appearance marked One Direction's final performance before their planned hiatus. Horan and bandmates Liam Payne, Harry Styles and Louis Tomlinson will take a year-long break to pursue their respective solo careers.
"5 of the best years of our lives so far," Horan wrote Monday on Twitter. "Thank you all so much for your incredible support. I hope you guys realise what you've done for us. Can't thank you enough to be honest ... Don't worry, we'll be back .. Looking forward to chilling for a while now."
Gomez previously dated singer Justin Bieber, and reunited with ex-boyfriend DJ Zedd to perform at the iHeartRadio Z100 Jingle Ball concert Friday. She released her second studio album, Revival, in October, and will next star in The Revised Fundamentals of Caregiving.