The Wizards of Waverly Place actress was appearing on The Late Show With David Letterman when the host displayed a photo of herself and Bieber at a recent event together.
"That was taken at the Vanity Fair Oscars Party," she explained on Wednesday's episode of the CBS show. "It was like a little prom night."
The 18-year-old went on to say that she has known Bieber for two years and they met after the singer's manager called her mum, who acts as her own manager. Letterman then joked, "I heard he was your paperboy!", to which Gomez laughed: "I'm blushing!"
Letterman then asked directly whether the pair were dating, to which she would only say: "He's been in my life for so long and it's nice to have someone who understands what you are going through."
Gomez and Bieber have both insisted on multiple occasions that they are just friends. Gomez recently admitted that she felt "hurt" when she received criticism from the singer's fans because of their friendship, saying: "I don't feel like I'm doing anything wrong. I've been best friends with him for a very long time."
The star is currently promoting her new single 'Who Says', which is available for download now. She is also preparing for her first headline tour later this year, and will perform at the upcoming Concert For Hope at the Gibson Amphitheatre in Los Angeles on March 20, with proceeds going to cancer charity City Of Hope.