White was born in Mt. Vernon, New York, the youngest child of Samuel White, a piano manufacturer, and Jessie Hart. He served in the army before going on to college. White graduated from Cornell University with a Bachelor of Arts degree in 1921. He picked up the nickname "Andy" at Cornell, where tradition confers that moniker on any male student surnamed White, after Cornell co-founder Andrew Dickson White. While at Cornell, he worked as editor of The Cornell Daily Sun with classmate Allison Danzig who later became a sportswriter for The New York Times. White was also a member of the Quill and Dagger society and Phi Gamma Delta (FIJI). He wrote for The Seattle Times and Seattle Post-Intelligencer and worked as an ad man before returning to New York City in 1924.

White married Katharine Sergeant Angell in 1929, also an editor at The New Yorker, and author (as Katharine White) of Onward and Upward in the Garden. They had a son, Joel White, a naval architect and boatbuilder, who owned Brooklin Boatyard in Brooklin, Maine. Katharine's son from her first marriage, Roger Angell, has spent decades as a fiction editor for The New Yorker and is well-known as the magazine's baseball writer.

White died on October 1, 1985, at his farm home in North Brooklin, Maine. He was buried beside his wife at the Brooklin Cemetery.

He published his first article in The New Yorker magazine in 1925, then joined the staff in 1927 and continued to contribute for around six decades. Best recognized for his essays and unsigned "Notes and Comment" pieces, he gradually became the most important contributor to The New Yorker at a time when it was arguably the most important American literary magazine. From the beginning to the end of his career at the New Yorker he frequently provided what the magazine calls "Newsbreaks", these being short, witty comments on oddly-worded printed items from many sources, under various categories such as "Block That Metaphor." He also served as a columnist for Harper's Magazine from 1938 to 1943.

In the late 1930s, White turned his hand to children's fiction on behalf of a niece, Janice Hart White. His first children's book, Stuart Little, was published in 1945, and Charlotte's Web appeared in 1952. Stuart Little received a lukewarm welcome from the literary community at first, due in part to the reluctance to endorse it by Anne Carroll Moore, the retired but still powerful children's librarian from the New York Public Library. However, both went on to receive high acclaim and in 1970, jointly won the Laura Ingalls Wilder Medal, a major prize in the field of children's literature. In the same year, White published his third children's novel, The Trumpet of the Swan. In 1973, that book received the Sequoyah Award from Oklahoma and the William Allen White Award from Kansas, both of which were awarded by students voting for their favorite book of the year.

In 1949, White published Here Is New York, a short book based upon a "Holiday" magazine article that he had been asked to write. That prescient "love letter" to the city was re-published in 1999 on the one-hundredth anniversary of his birth, with an introduction by his stepson, Roger Angell.

In 1959, White edited and updated The Elements of Style. This handbook of grammatical and stylistic guidance for writers of American English had been written and published in 1918 by William Strunk, Jr., one of White's professors at Cornell. White's rework of the book was extremely well received, and further editions of the work followed in 1972, 1979, and 1999; an illustrated edition followed in 2005. That same year, a New York composer named Nico Muhly premiered a short opera based on the book. The volume is a standard tool for students and writers and remains required reading in many composition classes. The complete history of The Elements of Style is detailed in Mark Garvey's A Slightly Obsessive History of Strunk & White's The Elements of Style.

In 1978, White won an honorary Pulitzer Prize for his work as a whole. Other awards he received included a Presidential Medal of Freedom in 1963 and memberships in a variety of literary societies throughout the United States.

A 1973 Canadian animated short, The Family That Dwelt Apart, is based on his short story of the same name.