Horan was recently linked to 20-year-old drama student Amy Green after reportedly introducing her as his girlfriend at an X Factor taping in Wembley.
The 'What Makes You Beautiful' singer has now been questioned about the state of his love life in an interview with Now magazine.
"[I'm] definitely single," Horan insisted, adding: "I'm not actually looking but if the right person came along, [I'd] definitely [want a girlfriend]."
He was also quizzed on sharing a kiss with Katy Perry at the 2012 MTV Video Music Awards earlier this year.
"Oh man - she's amazing! I think she feels a little bit of ownership over me because she was the one to put me through on X Factor when she was a guest judge," he recalled.
"I don't mind - she isn't a bad person to be making comments on ya! Katy's super-hot. And she's really cool as well. She was the first person to say hi backstage. Our dressing room was next to hers and we were just chatting and stuff."
He added specifically of kissing Perry: "Well, walking up those stairs the first thing I saw was her with her lips out. I forgot about the award at that moment - I just went straight for her lips!"
Read Niall Horan's full interview in Now magazine, on sale from Tuesday, October 30.
Earlier today, One Direction premiered a lyric video for their new single 'Little Things'.
Watch One Direction's 'What Makes You Beautiful' music video below: