The actress and celebrity chef can be heard on Friday's edition of the children's program.
"After learning about Monty and Vanessa's secret relationship, Carl bribes Monty into helping him get some much-needed acknowledgement from Monogram. Meanwhile, Candace is ecstatic when she discovers that her neighbor Peggy McGee has witnessed all of Phineas and Ferb's summer antics and is happy to tell Mom about them," a synopsis said.
The show is about Phineas and Ferb, elementary school-age stepbrothers with wild imaginations whose antics drive their teen sister Candace crazy.
Hawn will play Peggy in Friday's installment of the show and Ramsay will play a character named Chef.