Ehlert grew up painting and sculpting. Even in her early years-she always erased her drawings and was never satisfied. Her favorite art technique was and remains to this day to be cutting and pasting. This method is called collage—the process of cutting out pieces of paper, fabric, or objects and gluing them to a backing. 
Ehlert was born and raised in Beaver Dam, Wisconsin. She claims that she grew-up “in a home where everyone seemed to be making something.”
Her mother was a seamstress who taught her how to sew at 8 years old. Her mother also shared fabric scraps with her, which gave her art exposure early on. Her father had a basement workshop and always had art supplies available, just not the traditional supplies. He had materials like scrap lumber and nails. 
Ehlert graduated from the University of Wisconsin–Madison with a degree in English and Psychology. Then she went to the Layton School of Art. After getting her degree she worked as an apprentice in an art studio delivering illustrations. Here, Ehlert was able to work in the evenings on her own art. 
Ehlert has her own book creation process. She begins with a “dummy book” made from pencil drawings. Then, Ehlert assesses to determine the subject matter of the new book. Once she has a topic, she will do background research to learn more. Then she will begin her artwork, which involves cutting out each piece individually and then gluing them on the pages of her book.
Ehlert won the Caldecott Honor Book in 1989 for Color Zoo and won a Publishers Weekly Best Book of the Year for Snowballs. Ehlert became the Booklist Editors' Choice for Cuckoo/Cucú: A Mexican Folktale/Un cuento folklórico Mexicano. She also was awarded the IRA Teachers' Choice and NCTE Notable Children's Trade Book in the Language Arts for Feathers for Lunch and received the American Library Association Notable Children's Book and Boston Globe – Horn Book Award for Chicka Chicka Boom Boom. She received an Honorable Mention from the National Outdoor Book Award (Children's Category) in 2005 for Leaf Man.
- Angel Hide and Seek (illustrator)
- Chicka Chicka Boom Boom (illustrator)
- Growing Vegetable Soup
- Color Farm
- Color Zoo
- Crocodile Smile (illustrator)
- Cuckoo: A Mexican Folktale
- Market Day/Día de marcado
- Planting a Rainbow
- Eating the Alphabet
- Red Leaf, Yellow Leaf
- Fish Eyes
- Feathers for Lunch
- Nuts to You!
- In My World
- Moon Rope/Un Lazo a La Luna
- Mole's Hill: A Woodland Tale
- Thump, Thump, Rat-a-Tat-Tat (illustrator)
- A Pair of Socks (illustrator)
- Planting a Rainbow
- Top Cat
- Under My Nose
- Waiting for Wings
- Nuts to You
- Leaf Man
Color Zoo is one of her more famous books. Ehlert won the Caldecott Honor Award for this book. It is very simple and easy. Ehlert used shapes to create animals. She created an educational book with only shapes and colors. She names the shapes and then has the name of the animal on the next page. This book is enjoyable for all ages.