She was the illustrator of several award winning books, including the Newbery Medal winner Miss Hickory (1946) by Carolyn Sherwin Bailey, the Newbery Honor book My Father's Dragon (1948) by her stepdaughter Ruth Stiles Gannett, and the Caldecott Honor book My Mother Is the Most Beautiful Woman in the World (1945) by Becky Reyher.

She also studied at the Art Students' League Her teachers included Winold Reiss, Norman Bel Geddes, and Adolfo Best Maugard.

[1] Most of Gannett's work was illustrating children's books, and her work on My Mother Is the Most Beautiful Woman in the World (1945), Miss Hickory (1946), and My Father's Dragon (1948) was singled out for critical praise.

She also illustrated a number of adult novels, including Tortilla Flat (1937) by John Steinbeck [1] Ruth Chrisman Gannett died on 8 December 1979 in West Cornwall, Connecticut.

Her second husband was Lewis Stiles Gannett, author, journalist, and critic.