Jessica Whelan battled through a 13-month fight against stage four neuroblastoma.
Her father, Andy, made the announcement Sunday morning, writing:
"I feel both sadness and relief in informing you all that Jessica finally found peace at seven o'clock this morning. No longer does she suffer, no longer does she feel the pain of the physical constraints of her body. Now my princess has grown her angel wings and has gone up to play with her friends and loved ones. She will now watch down over her little brother and ourselves until one day we are reunited again."
Andy Whelan, a British photographer, routinely shared photos of his daughter's fight against neuroblastoma on this Facebook page. But he described the black-and-white photo of his daughter writhing in pain, with tears streaming down her face as "the hardest photograph I have ever made."
"This is the true face of cancer, my baby girl's blood vessels protruding from beneath her skin, a solitary tear running down her cheek, her body stiffened and her face contorted in pain," Whelan wrote on Facebook.
Whelan said he shared the painful photo not to upset anyone, but to bring awareness to childhood cancer.
"Please I beg of you, as a heartbroken father, it is too late for my daughter, but childhood cancer needs to be cured. No family should have to go through this hell," Whelan wrote.
Read his full Facebook post below.