Meresankh III was a daughter of Kawab and Hetepheres II, and thus a grand-daughter of Kheops, during whose reign she was born. Although her father never became a king, she bore the title "daughter of the king" among her titulary.
This may indicate that this title may not be taken too literally and may perhaps also mean "grand-daughter of the king". It may, however, also be explained by the fact that Meresankh became the step-daughter of king Djedefre, after the death of her father.
She was married to her uncle, Khefren, with whom she had as sons Nebemakhet, Niuserre, Khenterka and Duaenre. She also bore him a daughter, Shepsestkau and two other children.
She out-lived her husband for a short time and died during the early years of Mykerinos. No tomb seems to have been prepared for her when she died, which may indicate that she died unexpectedly. Her mother, Hetepheres II, donated her own mastaba tomb, discovered in April 1927 by George Reisner and known today as G 7530-7540, and sarcophagus for the burial of Meresankh III.
A statue pair showing Meresankh III to the left of Hetepheres II was found in the rubble nearby the mastaba. It may originally have stood in a niche in the mastaba's wall. Today, it is in the Boston Museum of Fine Arts.
The sarcophagus found in the burial chamber still contained some human bones, belonging to a woman who died in her fifties, perhaps Meresankh III herself.