Cheryl, who has five-month-old son Bear with boyfriend Liam Payne, took to Twitter to congratulate the royal couple.
"Awww congratulations to Will and Kate on their baby news!! 3rd royal baba on its way (sic)" she wrote.
The pair already has two children together - Prince George and Princess Charlotte - aged four and two.
George is set to start school in London this week and Charlotte celebrated her second birthday on May 2 this year.
Disclaimer: No Business Standard Journalist was involved in creation of this content