The singer wrote 'We Own the Night' which was recorded by Selena Gomez and the Scene for her last album, 'When the Sun Goes Down', and although they have yet to meet, Pixie is glad they worked together.
Speaking at the recent MTV Titanic Sounds concert in Belfast, Northern Ireland, Pixie exclusively told BANG Showbiz: ''I've never met Selena Gomez before, but she sounds really good on the song and she seems like a lovely girl.
''She seems to have such a zest for life, so I emailed her and said, 'Thanks for recording the song,' and she emailed back saying, 'No worries, that's fine, thanks!'''
Pixie has previously written tracks recorded by Alexandra Burke and Girls Can't Catch, but also for artists further afield, such as Dutch winner of 'The X Factor' Lisa Lois and Asian girl group Girl's Generation.
She added: ''I only have 12 songs on my album, so all the ones I write that don't make it get sent off by my publishers and luckily some of them get picked up. A lot of them are hits in other countries like Belgium or Holland, so most people in the UK don't know about them.''
Pixie's performance at MTV Titanic Sounds will be shown in the UK on MTV music on May 5.