Newton-John said the ghosts of friends and family who have passed on would constantly be floating around her and gave her guidance and strength through her most challenging times.
Her top spiritual guides included Karen Carpenter and John Denver.
"I often feel as if they hover around me when I perform," she said of their spirits. "They are my spirit guides who I ask to support me before every show and they keep me strong. They're gone, but their love never dies."
Denver was killed in a plane crash in 1997. Carpenter, known for her hits like We've Only Just Begun, was a good friend of Newton-Jones. The actress was supposed to have lunch with the singer the day after she died and learned about her passing on the radio.
Carpenter passed away in 1983 after suffering heart failure following an eating disorder.
"It was as if the sky fell to Earth," Newton-John said of hearing about her death. "My stomach hit the ground."
Besides Carpenter and Denver, the actress revealed she had also been visited by the spirit of her goddaughter, who died at 5 years old.
"She has been with me ever since, along with my parents, my sister and close friends who have passed away," she wrote in her book Don't Stop Believin' of Colette Chuda's death.
Newton-John said her "hands were shaking" when she learned about Colette's passing right before taking the stage.
"How could we live without Colette? My emotions were completely out of control," she recalled. "My emotions were completely out of control. I didn't know how I would sing I Honestly Love You without falling to my knees and weeping in front of the audience."
She knew the death would ruin her performance so she looked to Colette's spirit for help.
"'Colette,' I said out loud. 'I know you're with me. Please show me you're here so I have the strength to walk out on that stage and sing,'" she remembered saying. Newton-John then explained to the readers how she knew the child was with her.
"In the next moment, I felt what can best be described as a rush of cool air. It was like a caress, as if something had lovingly brushed up against my face ... it felt like a wing, and it was so very real. It was as if she was telling me that it was okay. To go on... I didn't break down onstage because I knew that little angel was with me."
As RadarOnline.com reported, Newton-John died peacefully surrounded by her family and friends at the age of 73. Like she said about the spirit guides in her book, "They're gone, but their love never dies."