Halberstam was raised in Yonkers, New York and, earlier, had lived in Winsted, Connecticut (where he was a classmate of Ralph Nader). In 1955, he graduated from Harvard University with a bachelor of arts, and he served as managing editor of The Harvard Crimson. His journalism career began at the Daily Times Leader, the smallest daily newspaper in Mississippi. He covered the beginnings of the American Civil Rights Movement for The Tennessean in Nashville.

In the mid-1960s, Halberstam covered the Civil Rights Movement for The New York Times. In the spring of 1967, he traveled with Martin Luther King Jr. from New York City to Cleveland and then to Berkeley for a Harpers article, "The Second Coming of Martin Luther King." While at the Times, he gathered material for his book The Making of a Quagmire: America and Vietnam during the Kennedy Era. In 1963, he received a George Polk Award for his reporting at The New York Times, including his eyewitness account of the self-immolation of Vietnamese Buddhist monk Thích Qu?ng Ð?c. monk During the Buddhist crisis, he and Neil Sheehan debunked the claim by the regime of Ngo Dinh Diem that the Army of the Republic of Vietnam regular forces had perpetrated the Xa Loi Pagoda raids, which the American authorities initially believed, and that instead, the Special Forces loyal to Diem's brother Ngo Dinh Nhu had done so to frame the army generals. He was also involved in a scuffle with Nhu's secret police after they punched fellow journalist Peter Arnett while the pressmen were covering a Buddhist protest. At age of 30, he was awarded a Pulitzer Prize for his war reporting. He is interviewed in the 1968 documentary film on the Vietnam War entitled In the Year of the Pig.

Halberstam next wrote about President John F. Kennedy's foreign policy decisions about the Vietnam War in The Best and the Brightest. Synthesizing material from dozens of books and many dozens of interviews, Halberstam found what he saw as a strange paradox at the heart of the Vietnam War: that those who crafted the U.S. war effort in Vietnam were some of the most intelligent, best-connected men in America ...- "the best and the brightest" -... but that those same brilliant men could not conduct or even imagine anything but a bloody, disastrous course.

In 1972, Halberstam went to work on his next book, The Powers That Be, published in 1979 and featuring profiles of media titans like William S. Paley of CBS, Henry Luce of Time magazine and Phil Graham of The Washington Post.

In 1980 his brother, cardiologist Michael J. Halberstam, was murdered during a burglary. Halberstam made his only public comment related to his brother's murder when he and Michael's widow castigated Life magazine, then published monthly, for paying Michael's killer $9,000 to pose in jail for color photographs that appeared on inside pages of the February 1981 edition of Life.

In 1991, Halberstam wrote The Next Century, in which he argued that, after the end of the Cold War, the United States was likely to fall behind economically to other countries such as Japan and Germany.

Later in his career, Halberstam turned to sports, publishing The Breaks of the Game, an inside look at Bill Walton and the 1979-80 Portland Trail Blazers basketball team; an ambitious book on Michael Jordan in 1999 called Playing for Keeps; and on the baseball pennant race battle between the New York Yankees and Boston Red Sox, called Summer of '49.

In 1997, Halberstam received the Elijah Parish Lovejoy Award as well as an honorary Doctor of Laws degree from Colby College.

After publishing four books in the 1960s, including the novel The Noblest Roman, The Making of a Quagmire, and The Unfinished Odyssey of Robert Kennedy Halberstam wrote three books in the 1970s, four books in the 1980s, and six books in the 1990s, including his 1999 "The Children" which chronicled the 1959-1962 Nashville Student Movement. He wrote four books in the 2000s and was en route to completing at least two others when his life ended suddenly after a car accident. In the wake of the 9/11, Halberstam wrote a book about the attacks, Firehouse, which describes in detail Engine 40, Ladder 35 of the New York City Fire Department.

America and the Korean War, Halberstam's last book, was published posthumously in September 2007.

Halberstam died on April 23, 2007 in a traffic crash in Menlo Park, California near the Dumbarton Bridge. He was in the area to give a talk at an event at UC Berkeley and was on his way to Mountain View to interview Pro Football Hall of Fame quarterback Y.A. Tittle for a book about the 1958 NFL Championship. Halberstam's driver Kevin Jones, a graduate student at the UC Berkeley Journalism School who was given the opportunity to drive Halberstam to the interview by the department, pleaded no contest to misdemeanor vehicular manslaughter charges. Jones proceeded from a controlled left turn lane on California State Route 84 against opposing traffic and a red light, and his vehicle was then hit broadside on the front passenger side, with fatal consequences for his passenger, Halberstam. Jones was sentenced to 5 days in jail and 200 hours of community service.

After Halberstam's death, the book project was taken over by Frank Gifford, who played for the losing New York Giants in the 1958 championship game, and was published by HarperCollins in October 2008 with an introduction dedicated to Halberstam. In Memory of David Halberstam - CommonDreams.org

Halberstam was generous with his time and advice to other authors. To cite just one instance, author Howard Bryant in the Acknowledgments section of "Juicing the Game", his 2005 book about steroids in baseball, said of Halberstam's assistance: "He provided me with a succinct road map and the proper mind-set." Bryant went on to quote Halberstam on how to tackle a controversial non-fiction subject:`Think about three or four moments that you believe to be the most important during your time frame. Then think about what the leadership did about it. It doesn't have to be complicated. What happened, and what did the leaders do about it? That's your book."

The Pulitzer Prize-winning Korean War correspondent Marguerite Higgins was the most pro-Diem journalist in the Saigon press corps and she frequently clashed with her younger male colleagues such as Neil Sheehan, Peter Arnett and Halberstam. She derided them as "typewriter strategists" who were "seldom at the scenes of battle". She alleged that they had ulterior motives, claiming "Reporters here would like to see us lose the war to prove they're right."

Mark Moyar, a revisionist historian, Triumph Forsaken claimed that Halberstam, along with fellow Vietnam journalists Neil Sheehan and Stanley Karnow, helped to bring about the 1963 South Vietnamese coup against President Ngo Dinh Diem by sending negative information on Diem to the U.S. government, in news articles and in private, because they decided Diem was unhelpful in the war effort. Moyar claims that much of this information was false or misleading. Historian Jeremy Kuzmarov disagrees, writing that Moyar's analysis underplays the fact that Diem was a corrupt, brutal and unpopular dictator, who tortured and executed opponents without trial. Kuzmarov says that while Moyar raises some valid criticisms about the methodologies of Halberstam and Sheehan, responsibility for the coup ultimately lies with Washington policymakers. Sheehan, Karnow, and Halberstam all won Pulitzer Prizes for their post-war works on the war.

Newspaper editor Michael Young says Halberstam saw Vietnam as a moralistic tragedy, with America's pride deterministically bringing about its downfall. Young writes that Halberstam reduced everything to human will, turning his subjects into agents of broader historical forces and coming off like a Hollywood movie with a fated and formulaic climax. Young considers such portrayals of personalities to be both a gift and a flaw.