The 18-year-old has come forward saying that she feels "abandoned" by Lawson.
According to statements made by Charles' daughter to a British newspaper, Phoebe claims that she has not been in contact with the food star since she moved out of the Saatchi family home in London.
"Nigella has not spoken to me since she left our house on that Sunday when the newspaper story appeared," Phoebe said.
"She has behaved in a very cold-hearted way," she went on to say. "She has been my mother since I was seven or eight and has just abandoned me."
On July 3, Charles and Nigella were granted a "decree nisi," which under U.K. law is a routine, early-stage decree for divorce proceedings before a final ruling becomes binding.
The two had to wait six weeks before they can be granted a "decree absolute," which will finalize their divorce and put an end to their 10-year union.
The former couple separated soon after photos were published last month in The Mirror's Sunday People showing the former advertising bigwig grabbing his wife's throat during an argument at Scott's restaurant in Mayfair, London.
The images prompted an investigation by authorities, who ultimately gave Saatchi a warning for assault.
Saatchi announced on July 6 that the pair was getting a divorce. He and Lawson also later revealed that they have no plans to make financial claims against each other.
According to a statement obtained by E! News earlier this month, Lawson is represented by lawyer Fiona Shackleton, who is working to "ensure a swift and amicable resolution."
The statement added, "Both parties would appreciate privacy for themselves and their children at this difficult time."