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.
American Thighs was released on this day in 1994.