One-year-old Ayelet Galena suffers from a rare life-threatening congenital disorder.
Rihanna and 50 Cent were so touched by the young girl's plight that they immediately signed up for a blood test to determine if they could be donors.
Both have also called on their fans to follow suit, reports dailystar.co.uk.
"Can you help me find a lifesaver for baby Ayelet and other patients? Get swabbed (tested) because maybe YOU can save a life!" Rihanna posted on microblogging site Twitter.
"Gossip Girl" actress Leighton Meester, rapper Pharrell Williams and rock band Linkin Park have also lent their star power to the campaign to save the little girl.