The 'Standing in the Dark' singer reveals he has penned tracks for the boy bands for potential inclusion on their upcoming albums.
He told MTV UK: ''I have wrote a couple of songs for the guys but I've been writing for a few different artists. I started as a song writer so it's cool to not only have Lawson songs but to write songs for other artists.''
However, the 25-year-old singer-songwriter - who is also hard at work on the follow-up to his band's debut album 'Chapman Square' - says Union J haven't recorded any of his songs yet.
He added: ''I'm not working with them but I'm writing songs. They haven't taken anything yet so we're just pitching for a few different artists.''
Ambitious Andy has also set his sights on writing for other big names, including 'I Knew You Were Trouble' hitmaker Taylor Swift.
He said: I think there's a lot of people we'd love to collaborate with. Someone like Jessie J or Taylor Swift, that'd be great.''
Meanwhile, singer Olly Murs recently revealed he'd love to collaborate with Andy's band Lawson or McFly on a track for his next album.
OK Go are warning us of 'bad people on the rise'.
Depp received the Favourite Movie Icon award at the People's Choice Awards on Wednesday, and thanked fans for standing by him through a turbulent...