Bob Marley & the Wailers' song "High Tide or Low Tide" has been released as a download together with a powerful film about the crisis.
Stars like Beyonce, Jennifer Lopez, Justin Bieber and about 150 others have pledged to promote it and the cause on Facebook and Twitter.
The video can be purchased on the "I'm Gonna Be Your Friend" campaign website, iTunes and Bob Marley's Facebook page.
All proceeds from each sale go directly to the fundraising appeal for East Africa, where millions of children face starvation and lack of water.
The Associated Press contributed to this report.