Boon was born in the Netherlands, she moved at an early age and was subsequently raised in many countries including Mexico where she lived for ten years. She attended the Royal Academy of Art where she majored in graphic design.

After graduation she moved to London where she began writing and illustrating children's book. Her first book, Peterkin Meets a Star, was published by William Heinemann in England in 1983 and by Random House in North America a year later. She has written a total of seven books and in recent years has primarily focused on illustrating. She often collaborates with author Harriet Ziefert.

As Writer and Illustrator

• Hannah's Helpers (1993)
• 1 2 3 How Many Animals Can You See? (1987)
• Peterkin's Very Own Garden (1987)
• It's Spring, Peterkin (1986)
• Belinda's Balloon (1985)
• Peterkin's Wet Walk (1983)
• Peterkin Meets a Star (1983)

As Illustrator

• Grandma, Where Are You? (2005) written by Harriet Ziefert
• Grandpa, Will You Play With Me? (2005) written by Harriet Ziefert
• No Kiss for Grandpa (2001) written by Harriet Ziefert
• The Orchard Baby and Toddler Collection (1999) for Orchard Books
• Little Hippo's New Friend (1999) written by Harriet Ziefert
• Little Hippo's New School (1999) written by Harriet Ziefert
• The Orchard Children’s Treasury for Children of all Ages (1997) for Orchard Books
• Little Hippo's New House (1997) written by Harriet Ziefert
• Little Hippo's New Baby (1997) written by Harriet Ziefert
• Timothy's Numbers (1996) written by Harriet Ziefert
• Timothy's Shapes (1996) written by Harriet Ziefert
• Benjy Bear's Halloween (1996) written by Harriet Ziefert
• Benjy Bear's Christmas (1996) written by Harriet Ziefert
• Mommy Where Are You? (1988) written by Harriet Ziefert
• Daddy Can You Play With Me? (1988) written by Harriet Ziefert
• A Bun for Barney (1987) written by Joyce Dunbar
• Katie and the Smallest Bear (1985) written by Ruth McCarthy