Jackie Coogan was born in Los Angeles, California, to John Henry Coogan, Jr. (also known as "Big Jack" or "Jack, Sr.") (1886–1935), the son of John Henry Coogan, Sr. (1853–1932), and Lilian Rita Dolliver Coogan (1892 or 1895–1977). He began his acting career as an infant in both vaudeville and film, with an uncredited role in the 1917 film Skinner's Baby. Charlie Chaplin discovered him in the Orpheum Theatre, Los Angeles, a vaudeville house, doing the shimmy, a popular dance at the time, on the stage. His father, Jack Coogan, Sr. was also an actor. The boy was a natural mimic, and delighted Chaplin with his abilities in this area. As a child actor, he is best remembered for his role as Charlie Chaplin's irascible sidekick in the film classic The Kid (1921) and for the title role in Oliver Twist, directed by Frank Lloyd, the following year. He was also one of the first stars to be heavily merchandised, with peanut butter, stationery, whistles, dolls, records, and figurines just a sample of Coogan merchandise on offer. He also traveled internationally, to be received by huge crowds. Many of his early films are lost or unavailable, but Turner Classic Movies recently presented The Rag Man with a new score. Coogan was famous for his pageboy haircut and his The Kid outfit of oversize overalls and cap, which was widely imitated, including by the young Scotty Beckett in the Our Gang films.

He was tutored until the age of ten, after which he attended Urban Military Academy and other prep schools, and then several colleges, including the University of Southern California. In 1932 he left Santa Clara University because of poor grades.

On May 4, 1935, Coogan was the sole survivor of a car crash in San Diego County that claimed the life of his father, and his best friend Junior Durkin, a child actor best known as Huckleberry Finn in two films of the early 1930s. The accident took place just short of Coogan's twenty-first birthday.

Coogan has a star on the Hollywood Walk of Fame in front of 1654 Vine Street, just south of Hollywood Boulevard.

In November 1933 Brooke Hart, a close friend of Coogan's from Santa Clara University, was kidnapped from his family-owned department store in San Jose and brought to the San Francisco area San Mateo - Hayward Bridge. After several demands for a $40,000 ransom, police arrested Thomas Thurmond and John Holmes in San Jose. Thurmond admitted that Hart had been murdered on the night he was kidnapped. Both men were then transferred to a prison in San Jose, California. Later a mob broke into the building; Thurmond and Holmes were then hanged in an adjacent park. Coogan is reported to have been one of the mob that prepared and held the lynching rope.

As a child star, Coogan earned an estimated $3 to $4 million (adjusted amount ranges from $40 million to $100 million), but the money was taken by his mother, Lilian, and stepfather, Arthur Bernstein, for extravagances such as fur coats, diamonds, and cars. Coogan sued them in 1938 (aged 23), but after legal expenses, he only received $126,000 of the approximately $250,000 remaining. When Coogan fell on hard times, Charlie Chaplin gave him some financial support.

The legal battle did, however, bring attention to child actors and resulted in the state of California enacting the California Child Actor's Bill, sometimes known as the Coogan Bill or the Coogan Act. This requires that the child's employer set aside 15% of the child's earnings in a trust, and codifies such issues as schooling, work hours and time-off. Jackie's mother and stepfather attempted to soften the situation by pointing out that the child was having fun and thought he was playing. However, virtually every child star from Baby Peggy on has stated that they were keenly aware that what they were doing was work.

Coogan enlisted in the United States Army in March 1941. After the attack on Pearl Harbor, he requested a transfer to United States Army Air Forces as a glider pilot because of his civilian flying experience. After graduating from glider school, he was made a flight officer and he volunteered for hazardous duty with the 1st Air Commando Group. In December 1943, the unit was sent to India. He flew British troops, the Chindits, under General Orde Wingate on March 5, 1944, landing them at night in a small jungle clearing 100 miles behind Japanese lines in the Burma campaign.

After the war, Coogan returned to acting, taking mostly character roles and appearing on television. 1952-1953 he played Stoney Crockett in 39 episodes of Cowboy G-Men. He guest starred as Corbett in two episodes of NBC's The Outlaws with Barton MacLane, which aired from 1960–1962. In the 1960–1961 season, he guest starred in the episode "The Damaged Dolls" of the syndicated crime drama The Brothers Brannagan.

Coogan had a regular role in a 1962–1963 NBC series, McKeever and the Colonel. He finally found his most famous television role as Uncle Fester in ABC's The Addams Family (1964–1966) as one of the older cast members; he was already in his fifties as this time. He appeared as a police officer in the Elvis Presley comedy Girl Happy in 1965. He had a role in the 1969 movie Marlowe.