Chapman has been widely associated with the book The Catcher in the Rye, which he carried with him at the time and claimed would explain his perspective. Various specific motivations have also been suggested. Chapman has since stated that what he did was wrong. There have been a number of interviews, books and films concerning Chapman and the murder of Lennon.

Chapman was born in Fort Worth, Texas. His father, David Curtis Chapman, was a staff sergeant in the United States Air Force, and his mother, Kathryn Elizabeth Pease, was a nurse. His younger sister, Susan, was born seven years later. He said that he lived in fear of his father as a child, who was physically abusive towards his wife and son. He also fantasized about having god-like power over a group of imaginary "little people".

Chapman attended Columbia High School in Decatur, Georgia. By the time he was 14, he used drugs, sometimes skipped classes, and once ran away from home to live on the streets for two weeks. Chapman reported that he was bullied because he was not a good athlete. His favorite band was The Beatles. He took marijuana, LSD, heroin, mescaline and barbiturates.

At age 16, Chapman became a born-again Christian, and distributed Bible tracts. He met his first girlfriend, another born-again Christian named Jessica Blankenship. He began work as a YMCA summer camp counselor; he was very popular with the children, who nicknamed him "Nemo". He won an award for Outstanding Counselor and was made assistant director. Those who knew him in the caretaking professions unanimously called him an outstanding worker.

A friend recommended The Catcher in the Rye to Chapman, and the story eventually took on great personal significance for him, to the extent that he reportedly wished to model his life after its protagonist, Holden Caulfield.

After graduating from Columbia High School, Chapman moved for a time to Chicago and played guitar in churches and Christian nightspots while his friend did impersonations. He worked successfully at the YMCA with Vietnamese refugees at a resettlement camp at Fort Chaffee in Arkansas, after a brief visit to Lebanon for the same work. He was named an area coordinator and a key aide to the program director, David Moore, who later said Chapman cared deeply for the children and worked hard. Chapman accompanied Moore to meetings with government officials, and President Gerald Ford shook his hand.

Chapman joined his girlfriend, Jessica Blankenship, as a student at Covenant College (an evangelical Presbyterian college that emphasizes the liberal arts) in Lookout Mountain, Georgia. However, Chapman fell behind in his studies and became obsessed with guilt over having an affair. He started having suicidal thoughts and feeling like a failure. He dropped out of Covenant College, and his girlfriend broke off their relationship. He returned to work at the resettlement camp, but left after an argument. Chapman then took a job as a security guard, eventually taking a week-long course that qualified him to be an armed guard. He made another attempt to go to college but dropped out again. He decided to go to Hawaii and then kill himself.

In 1977, Chapman attempted suicide via carbon monoxide asphyxiation. He connected a vacuum cleaner hose to his car exhaust pipe and led it inside the car, thus exposing himself to the car's exhaust, but the hose melted in the exhaust pipe and the attempt failed. He was discovered and brought to a local mental health clinic. A psychiatrist admitted him to Castle Memorial Hospital for clinical depression. Upon his release, the hospital hired him part-time. He played guitar for the patients and counseled them. He found a place to live with a Presbyterian minister. His parents began divorce proceedings, and his mother joined Chapman in Hawaii.

During his stay in Hawaii from 1978 to 1980, Chapman went to several art galleries. According to the Vice President of Center Art Gallery, Chapman was repeatedly presented with an investment perspective sales presentation of fine art specifically related to the artist Salvador Dalí. The premise of the sales presentation was to purchase art from a prolific artist who was still living before the artist's death. It was implied that the artist's work would escalate in value upon his death. Chapman told sales staff that he collected items of living artists, which he was hoping would become more valuable upon their death. He once mentioned to a sales manager that he thought it was almost a compliment to a great artist that his work would become far more valuable upon his death.

In 1978, Chapman went on a six-week trip around the world, inspired partly by the film Around the World in Eighty Days, visiting such places as Tokyo, Seoul, Hong Kong, Singapore, Bangkok, Delhi, Israel, Geneva, London, Paris, and Dublin. He began a relationship with his travel agent, a Japanese-American woman named Gloria Abe. They married on June 2, 1979. Looking for more money, Chapman got a job at Castle Memorial Hospital as a printer, working alone rather than with staff and patients. He then got into an argument with Abe's boss at the travel agency and made her quit and find another job. He was then fired by the Castle Memorial Hospital, rehired, then got into a shouting match with a nurse and quit. He took a job as a night security guard and began drinking heavily.