Beyoncé first met Chelsea Lee James in 2009, when she invited the girl to join her on stage to perform "Halo."
After Chelsea, 15, died of cancer a few days ago, the singer remembered her grieving family.
Beyoncé, 32, sent the girl's Australian family a bouquet of white roses, along with a personalized note, according to a post on a support page for Chelsea.
"Donna, Love and prayers to you and your family," she wrote to the girl's mom. "Chelsea was a beautiful girl and I am so happy I was able to meet her. She touched my heart and I will never forget her."
Chelsea died April 21 after a decade-long battle with cancer. In 2004, she was first diagnosed with a tumor on her spine. Despite surgery, chemotherapy and radiation, the tumor multiplied, eventually numbering 18. Meeting Beyoncé was a dream come true for the British girl, who reunited with the singer last year.
"I was so excited to meet Beyoncé again," she said, according to a media report. "This time ... I actually got to meet her backstage and talk to her and laugh with her, which was so cool. I'll never forget this."
A rep for the singer could not be reached for comment.