The 23-year-old singer partied with the 'As Long As You Love Me' hitmaker in Monaco earlier in the year and all he could talk about was his ex, who he enjoyed an on/off relationship with for four years.
Speaking of her encounter with 20-year-old Justin, Pixie said: ''When I was in the South of France I bumped into Justin Bieber and we were both talking about how elegant and beautiful [Selena] is.''
The 'All About Tonight' hitmaker also revealed she'd love to join Selena back in the studio after the pair recorded 'We Own The Night' together three years ago.
She told the Metro newspaper: ''I think she is so lovely and beautiful. She is really talented.
''Selena recorded a song I had written and she left my parts in on the middle eight so it ended up being Selena Gomez featuring Pixie Lott.''
The feeling is certainly mutual as Selena previously revealed her love of Pixie's voice.
Selena said: ''I love Pixie very much. She wrote a song [for my album] and I'm obsessed with it, I think it's a beautiful song.
''Originally I was just going to have the song and not feature her but I love her voice so much.
''I listened to the original version with her singing it more just because her voice is so beautiful. I wanted to keep some of the ambience she had on the record therefore we featured it.''