The soap star, who plays Sonia Fowler, shared the devastating news on Instagram.
In front of a selfie with her dad, Natalie wrote: “I have been very calm the past few weeks. I lost my precious daddy three weeks ago today.
“I wasn’t really going to do this post, but I felt like I couldn’t come here and be a button without everyone knowing that my life has changed.
“He was my whole world and I’m not sure what I’m going to do without him. All I know is that my family, my friends and my job will make it easier. I can’t believe how lucky I am to have such wonderful people in my life. “
She continued, “It’s really about these times that you realize how important relationships are and that companionship, friendship and love are so important. Losing someone is difficult. NEVER seeing someone again is cruel. But it is part of life. And we continue. and have our memories.
“Charles William Cassidy 1937-2021. The best dad and grandfather in the world. We miss you so much but we are each other because of you, ”she added.
Natalie was instantly inundated with supportive messages from friends and fans, with her former EastEnders co-star Jacqueline Jossa writing, “Sorry to hear this beautiful girl, I love you and your family.
Scarlett Moffatt left a chain of love hearts on her post, while a fan wrote: “I’m so sorry for your loss. I’m so glad you posted your Masters tradition with your dad. What a beautiful memory to have. “
Natalie had moved in with her father, her partner Marc Humphreys and their two children – Eliza, 10, and Joanie, four.
In October last year, she spoke of her fear of losing him after her mother died when she was just 19 years old.
“The last few days have been a bit of a challenge,” she told her fans at the time after Charles got a health scare.
“Dad isn’t doing very well, nothing serious, but it makes you realize they won’t be here forever.”
“Losing mom young means we’re so close, in my head I feel like he’s always going to be that age, live with me and be a little cranky at times.
“But we know that’s not true. He’s as strong as an ox, so I hope he sticks around for a long time to come. Losing people is such a difficult part of our life no matter how old they are or how they are spending.
“Here is for all those who have lost that special someone, who are always leaving, who some days may not feel like it’s worth it, and other days they laugh and joke like others.
“We have good days, bad days, between days. But you go on and enjoy your life, because that’s what they would like us to do. Good Tuesday. “