The rocker headed into the studio with his twin brother Benji earlier this month (Dec12) to record a festive tune, entitled Let The World Be Still, for the United Nations Children's Fund (Unicef).
The siblings premiered the track over the weekend (15-16Dec12), and revealed that Joel and Nicole's four-year-old daughter Harlow designed the cover art, which features a smiling Father Christmas.
In a post on his Twitter.com page, Joel writes, "Cover art for our Christmas single Let The World Be Still. Drawn by my favourite artist, Harlow Madden. All the proceeds will go to our favourite cause Unicef. 'Tis the Season!"
Benji adds, "My little niece Harlow did the cover art for our Christmas song... Happy holidays from The Madden Brothers."