Elizabeth Borton de Trevino was born in Bakersfield, California, on September 2, 1904, to Fred Ellsworth Borton, a lawyer, and Carrie Borton. Her first home was a four room wooden cottage, from which the Bortons moved across town in about 1909 in order for Fred to be closer to his office in the Producer's Bank Building. In 1910 Elizabeth contracted malaria, and she began spending her summers with her grandmother in the healthier climate near the ocean. Elizabeth's parents and her grandmother all enjoyed reading and encouraged her to read; she spent many hours in the public library. Her father, in particular, encouraged her to write, teaching her the self-discipline necessary for successful writing. When young Elizabeth's first poem was published in the Monterey Peninsula Herald in 1912, she knew that she wanted to be a professional writer.

In 1925 Trevino graduated with a bachelor of arts degree in Latin American history from Stanford University. From 1925 to 1934, she studied violin at the Boston Conservatory of Music and worked as a newspaper reporter for the Boston Herald, beginning as an assistant music reviewer. She enjoyed the life of a newspaper reporter and in 1934 won an assignment to journey to Mexico to write a series of articles about some of Mexico's leaders. While on this assignment, she met Luis Trevino Gomez, who had been assigned as her escort by the Monterrey Chamber of Commerce. By the time Elizabeth finished her reporting assignment, she and Luis were engaged to be married. Their wedding was held on August 10, 1935, and they made their first home in Monterrey, in Nuevo Leon State, Mexico. The couple later Elizabeth B. de Trevino 607 moved to San Angel, near Mexico City, where Luis, an ambitious insurance and real estate agent, could be closer to Mexico's centers of power.

Although Trevino continues to reside in Mexico, now in Cuernavaca in Morelos State, she has remained an American citizen. During her years in Mexico, she has raised two children and worked as a secretary, while also writing books for young readers and adults. In 1966 her novel I, Juan de Pareja won the Newbery Medal for the outstanding American children's book of 1965.

Like several of her other books, I, Juan de Pareja was inspired by Trevino's study of Spanish culture. The important seventeenth-century Spanish painter Velazquez had painted a portrait of his black slave Juan de Pareja, whom he later freed and who became a significant painter in his own right. This portrait inspired Trevino to write her historical novel about Pareja. In the same year that Trevino won the Newbery Medal, the Wildenstein Gallery of New York bought the painting for $5,544,000, then a record price for an auctioned painting. Customarily called The Slave of Velazquez, it reveals a man of great dignity.