In a statement, Sky and Amanda Roberts said the visit would take place two days after the first anniversary of Giuffre taking her own life.
"We strongly urge King Charles to meet with us and survivors and hear what we have to say," they said.
"We are thankful to him for heeding our sister's allegations against Andrew Mountbatten-Windsor, and for his decisive action in stripping his brother from his position as a prince."
Buckingham Palace didn't respond to a request for comment.
Palace officials have previously said the king could not become involved while investigations connected to sexual abuse by Epstein and his circle remain ongoing.
Giuffre accused the late US financier Epstein of trafficking her to King Charles' younger brother, Andrew Mountbatten-Windsor, when she was 17.
Mountbatten-Windsor has always denied the allegations and reached an out-of-court settlement with Giuffre in 2022 without admitting wrongdoing.
He has said he had no recollection of meeting Giuffre.
Charles and his wife, Queen Camilla, are due to visit the United States from April 27 to 30 on a trip timed to mark the 250th anniversary of American independence.
The state visit comes as Britain seeks to steady relations with US President Donald Trump after tensions over the Iran war, placing additional attention on the monarch's program in Washington.
After renewed scrutiny over Mountbatten-Windsor's friendship with Epstein, the king moved to remove his brother from public life, stripping him of military roles, patronages and the use of his royal titles.
Mountbatten-Windsor was arrested earlier this year on suspicion of misconduct in public office over allegations he passed confidential documents to Epstein. He has denied wrongdoing.
The Roberts said they hoped the king would meet survivors of sexual abuse by Epstein and his circle directly and that dialogue with survivors and their families could lead to action by the British government against Epstein's co-conspirators.
Buckingham Palace has previously said that the royal family's "thoughts and utmost sympathies" were with victims and survivors of abuse.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
