Millions of families have been displaced since war broke out between rebels and President Bashar al-Assad's troops in the Middle Eastern country in 2011.
Ewan MCGregor has led a fundraising campaign as part of his role as an ambassador for the United Nations Children's Fund (Unicef), which aims to help youngsters facing a third winter in treacherous conditions.
Now Ora, Tempah and Bunton have appeared in a promotional film to urge Brits to donate money to help pay for winter clothing, shelter, food and medicine.
Ora says, "Right now, children in Syria are suffering unspeakable violence, often fleeing their homes with nothing but the clothes on their back. Now facing a third winter in cold tents, their lives are threatened by the freezing temperatures. Unicef works in more than 190 countries, from Kosovo to Syria and in all the countries providing refuge to Syrian children. Your donation could help Unicef buy life-saving winter essentials to help bring children in from the cold."
MCGregor adds, "My heart truly goes out to the millions of Syrian children who have lost everything: their families, friends and homes. Facing a third year in a freezing cold camp is no place anyone should call home, let alone a child. I worry that the world is starting to shut its eyes to the Syrian crisis."