A four-year-old girl with a rare blood disorder has touched the hearts of millions with a rendition of her favourite song, titled “Overcomer”.

In a video posted to Facebook on Sunday, Leah Carrol mimes, sings and dances to the gospel song.

“You might be down for a moment, feeling like it's hopeless, that's when he (God) reminds you, that you're an overcomer,” she can be heard singing along to the Mandisa tune.

The video has since received more than three million views and tens of thousands of reactions.

“She's an overcomer. Septic shock, two bone marrow transplants, graft vs host disease and 325 days away from home in the hospital,” Leah’s mother Lindsay Carroll wrote.

Mandisa herself has since shared Leah’s video and asked her followers to pray for the girl’s recovery.

Leah was diagnosed with Severe Congenital Neutropenia in 2013, which is a blood disorder that leaves sufferers prone to bacterial infections.

Her parents are seeking a bone marrow transplant to help correct her condition, and have launched a crowdfunding campaign.