Iversen, Presley’s mother and Keough’s great-grandmother, died peacefully in the early hours of Tuesday morning.
Sharing a photo of her on Instagram, 76-year-old Priscilla Presley — who was previously married to Elvis Presley — wrote: “I am heartbroken. My beautiful mother passed today. She was the light of our lives. She never wanted any attention on herself.
“Her children were her everything. May you Rest In Peace mom. You will always be with us.”
Keough was quick to share the same photograph, before making a tribute of her own by posting an old photograph of a young Iverson next to her husband, Paul Beaulieu, and a young Priscilla.
She added: "We lost our beautiful Nana this morning. She was an incredible woman and mother. Rest In Peace nana.”
Iverson was previously married to James Frederick Wagner, a US Navy pilot and her childhood sweetheart.
Tragically, he was killed in a plane crash just six months after their daughter Priscilla was born.
Iverson would later marry Beaulieu in 1944, and he would raise Iverson’s daughter as his own.
The tragic news comes just a year after the death of Benjamin Keough, Presley’s grandson and Keough’s brother.
He died by suicide in July 2020 at the age of 27.
Presley later stated that the loss of Benjamin was “devastating” and had “penetrated her soul” as their family — including her daughter and Ben’s mother, Lisa Marie — came to terms with the loss.
“Each day I wake up I pray it will get better,” Presley wrote in a Facebook statement. “Then, I think of my daughter and the pain she is going through as she was a doting mother.
“Ben’s father, Danny, who is completely lost, as Ben was his only son. Riley, so loving and so close to him; Harper and Finley, who absolutely adored Ben.
“Navarone [Lisa Marie’s brother], who struggles deeply with loss and death. Rest In Peace Ben, you were loved.”
Watch: Lisa Marie Presley seen in rare photo shared by daughter Riley Keough