Maynard contributed to Mademoiselle and Harrowsmith magazines in the 1980s, while also beginning a career as a novelist with the publication of her first novel, Baby Love (1981).

Maynard received significant media attention in 1998 with the publication of her memoir At Home in the World, in which she describes her relationship with J. D. Salinger.

After the article was published, Maynard received a letter from fiction writer J. D. Salinger, then 53 years old, who complimented her writing and warned her of the dangers of publicity.

[10][2] In 2021, Maynard wrote about the relationship in Vanity Fair in connection with the TV series Allen v. Farrow: "I was groomed to be the sexual partner of a narcissist who nearly derailed my life".

She went into detail about the other relationships with teenagers Salinger had had at the same time, adding, "When he sent me away less than a year later with words of contempt and disdain, I believed the failure was mine, and that I was no longer worthy of his love or even respect."

From 1984 to 1990, Maynard wrote the weekly syndicated column "Domestic Affairs", dealing with marriage, parenthood, and family life.

In 1986, Maynard helped lead the opposition to the construction of the nation's first high-level nuclear waste dump in New Hampshire, with ground zero in Hillsborough, where she lived with her family.

The government was planning to use technology never before tried and totally unproven as safe, to bury decades-worth of high-level nuclear waste in New Hampshire granite, and to create an entire highway and train system into the state to bring the extraordinarily dangerous material with a half life of a million years.

[clarify] Maynard and others rallied at town meetings and convoyed to Concord, and later that year, a law was passed prohibiting a nuclear waste dump in New Hampshire.

Her true crime book Internal Combustion (2006) deals with the case of Nancy Seaman, a Michigan resident convicted in 2004 of killing her husband.

The novel Labor Day was published in 2009 and adapted into a movie, written and directed by Jason Reitman and starring Kate Winslet and Josh Brolin.

That autumn, she won The Grand Prix de Littérature Américaine 2021 for "Où vivaient les gens heureux" (Count the Ways), published in France in August 2021 by Philippe Rey in a translation by Florence Lévy-Paoloni.

I wished I could reach through the pages I was reading out loud and put my arms around that girl, tell her to be careful of her body, her gifts, her precious and breakable heart.

They had three children together: daughter Audrey, a social worker, and sons Charlie, a DJ/music producer known as Captain Planet, and Wilson, an actor known for Hart of Dixie, Daredevil, and All Rise.

[citation needed] Maynard and her sister, Rona, a writer and retired editor of Chatelaine magazine, collaborated on an examination of their sisterhood.