Peggy Parish was born in Manning, South Carolina. She received a Bachelor of Arts degree in English from the University of South Carolina. After graduation, she visited her brother in Kentucky, and was persuaded to try teaching. She began by teaching creative dancing to young children. Later, she moved to Oklahoma where she taught both third grade and dance, and she produced community shows. She then moved to New York and got a job teaching dance to third-graders in a progressive experimental school called the Dalton School in Manhattan.

At this time she also began writing. Her first published book, My Golden Book of Manners, was published in 1961, followed by Let's Be Indians (1962). She created her most famous character with the publication of Amelia Bedelia in 1963. She went on to write 11 more Amelia Bedelia books, as well as other children's books, mystery novels, and arts and crafts books. She also produced television pieces on preschool education and children's books, wrote book review columns and led a number of training workshops for teachers.

She died suddenly in 1988 of a brain aneurysm. Her series Amelia Bedelia was continued by her nephew Herman Parish.