Born in Wilmington, Delaware, Katharine was the youngest child of William Pyle, a leather manufacturer, and Margaret Churchman Painter, an "amateur" writer.

In 1893, her art was exhibited at the World's Columbian Exposition, and by 1895, she had begun work as a professional author illustrator, with the publication of The Rabbit Witch and Other Stories (1895, republished in multiple editions as Careless Jane and Other Tales, from 1902).

That same year, she contributed the illustrations to Edith M. Thomas’s highly praised book of poetry, In Sunshine Land (1895).

The period between 1880 and 1914 is regarded as the Golden Age of Illustration in America, when the proliferation of expense-saving improvements in printing practices and a "newly literate public," aligned.

Howard Pyle was teacher and "sometime mentor" to a "whole school of American women illustrators," including Ethel Franklin Betts, Elizabeth Shippen Green, Charlotte Harding, Violet Oakley, Sarah S. Stilwell, Ellen Bernard Thompson (Pyle), and Jessie Wilcox Smith.

Her last titles continued to include materials and stories "seeming to lend themselves less adaptable for young people," and contemporary reviews did not always consider her to be up to this challenge.

[7] Some viewed these challenging later adaptations as evidence that Pyle possessed an "even more versatile genius" than her brother, extolling the author's work in discreetly softening "the darkness and brutality" in favor of "the heroism, the gorgeousness, the religious fervor and the magic" of the tales,[8] others did not find her touch so adept.