According to the biographical information published with that series, Helquist was born in Ganado, Arizona, and lived in Orem, Utah with his six sisters. As kids, they didn't go to many art museums. He says his love of art came from all the comic books he read. Brett earned a Bachelor's Degree in Fine Arts from Brigham Young University, and lives in New York City (as of 2004). He has been published in the children's magazine Cricket, and the New York Times. He is represented by Steven Malk of Writers House in New York City.
Besides the thirteen A Series of Unfortunate Events books, Helquist has provided illustrations for several other children's books, including:
Brett also wrote and illustrated Roger, the Jolly Pirate, ISBN 0-06-623805-6, published in 2004.
He also produced new cover illustrations for a recent reprint of the "Green Knowe" series: