Born to wealthy bluebloods William B. Emerson and Ruth Shaw Emerson, Gloria Emerson, who grew to 6' tall, spent some of her youth in Saigon. It was there that she first began to write for the newspapers, freelancing for The New York Times in 1956. Subsequently tiring of writing only about fashion, she returned to America and quit to get married. Returning in 1964 to the Times, she worked in the paper's London and Paris bureaus until she convinced the paper, as she said in the obituary she wrote for herself, "that she be sent to Vietnam because she had been in that country in 1956 and wanted to go back to write about the Vietnamese people and the immense unhappy changes in their lives, not a subject widely covered by the huge press corps who were preoccupied with covering the military story."

Among her first reports for The New York Times, Emerson exposed false "body counts" and "unearned commendations" to field-grade officers and the use of hard drugs by American soldiers. She also reported on the suffering of the Vietnamese people.

In her self-written obituary, which reporters at the Times discovered on the day she died, Emerson described the plaudits that came her way:

Her dispatches from Vietnam won a George Polk Award for excellence in foreign reporting, and, later, a Matrix Award from New York Women in Communications. Her nonfiction book on the war, Winners & Losers (Random House, 1977), won a National Book Award in 1978 but she described it as "too huge and somewhat messy". Its subject was the effects of the conflict on some Americans, or "an absence of the effect", as she once said.

One of the most quoted parts of the book was Emerson's condemnation of "killing at a distance":

Americans cannot perceive ... even the most decent among us ... the suffering caused by the United States air war in Indochina and how huge are the graveyards we have created there. To a reporter recently returned from Vietnam, it often seems that much of our fury and fear is reserved for busing, abortion, mugging, and liberation of some kind. ... As Anthony Lewis once wrote, our military technology is so advanced that we kill at a distance and insulate our consciences by the remoteness of the killing.

John Lennon and the anti-war movement

In December 1969, Emerson conducted a very contentious interview with John Lennon and Yoko Ono at the Apple Records headquarters in London, during which she disputed the effectiveness of Lennon and Ono's anti-war campaign, undertaken at great professional and financial cost to the Lennons. Her abrupt manner and skeptical approach enraged Lennon. Ironically, given Emerson's own anti-establishment positions, the interview became famous as an example of the establishment press resistance to the Lennons' peace movement. The interview was prominently featured in the 1988 documentary John Lennon and the 2006 movie The U.S. vs. John Lennon.

Emerson said at the time...and repeated decades later...that she believed the Beatles and Lennon "could have stopped the war" had they performed for U.S. troops in Vietnam.

Gaza, a Year in the Intifada

This 1991 book is about a year she spent in the occupied territories. "The book provoked hostility among friends, and others felt it was anti-Israel, but Ms. Emerson insisted this was not the reason for writing it," she explained in her obituary; "she hoped to provide a primer for those who felt the situation in the Middle East was too complicated or too controversial to understand." She won a 1991 James Aronson Award for Social Justice Journalism.

Loving Graham Greene

In 2000 Emerson published her only novel, Loving Graham Greene, described by William Boyd in The New York Times Book Review as "beguiling and memorable... a funny, moving and strangely profound novel". The novel sprang from Emerson's fascination with the British novelist Graham Greene whom she had interviewed in Antibes in March 1978 for the magazine Rolling Stone. It is set partly in Princeton, New Jersey, where she lived (and taught) for many years, and in Algiers, where she visited briefly in 1992 at the outset of the Algerian civil war which claimed the lives of an estimated 100,000 people. This fiction is the distillation of Emerson's experience as a journalist and an activist. This novel was the first book by Emerson to be translated into a foreign language and appeared in France in April 2007.

Emerson was diagnosed with Parkinson's Disease in 2004. Unable to contemplate a future in which she could not write, Emerson committed suicide on August 3, 2004.

On her application to the Times in 1957, Emerson described herself as a widow, giving her married name as Znamiecki. She was married to Charles A. Brofferio from 1960 to 1961.