In 1981, Forrest Gump is sitting on a bench at a bus stop, and he has decided to tell his life story to a nurse who is sitting on the bench next to him. As a young boy, Forrest wore leg braces because he had a curved spine and was unable to walk properly. He grew up in a boarding house in Alabama with his mother, who taught him to always believe in himself, in spite of his physical limitations. Additionally, Forrest has a below-average IQ. To get him accepted into a public school, Forrest’s mother agreed to sleep with the principal in exchange for Forrest's admission.
In flashback, Forrest meets Jenny Curran on the first day of school on the bus. The two become fast friends and they spend all their time together. Jenny is beautiful and a good friend to Forrest, but she struggles at home with a sexually abusive father. One day, when a group of children start bullying Forrest, Jenny tells him to run and he runs away, outrunning the bullies. In the process, his leg braces miraculously fall off his legs.
As time passes, Forrest and Jenny remain good friends. In high school, while running from some bullies, Forrest gets noticed by a football scout and accepted into college on a sports scholarship. During this time, the college gets desegregated and a number of black students are admitted, a historic event at which Forrest is present.
Forrest ends up meeting President Kennedy after getting recruited onto the All-American football team. After graduation, he joins the army and meets a friend at boot camp, Bubba, a young black man whose one dream is to start a shrimping business.
Forrest has an easy life in the army because he listens well and follows orders. While in the army, Forrest finds out that Jenny was expelled from college because she posed nude in a magazine wearing her school sweeter. Forrest goes to find Jenny in Memphis, where she is singing naked at a strip club. Forrest tells Jenny he loves her and that he is being sent to Vietnam.
In Vietnam, Forrest and Bubba are put under the command of Lieutenant Dan, an army officer who has had an ancestor die in every American war. The platoon in which Forrest serves gets attacked and Bubba is killed. In the midst of the attack, Forrest goes back and retrieves all his fellow soldiers, which wins him a medal of honor. He even saves Lieutenant Dan, even though Dan was intent on dying in battle, like his ancestors.
Forrest is sent to an army hospital after taking a bullet to his rear end in the battle. There, he is in a bed next to Lieutenant Dan, who lost both his legs in the attack. At the hospital, Forrest starts playing ping pong and is really good at it. Back in Washington, after receiving a medal of honor, Forrest is pulled into an anti-war demonstration where he runs into Jenny, who has become a hippie radical. She is also in an abusive relationship, which Forrest tries to protect her from to no avail.
Forrest plays ping pong internationally, and when he returns to New York to interview about his athletic prowess, he runs into Lieutenant Dan, who is in a wheelchair and living on disability. He stays with Dan for the winter holidays and the two of them become close. When Forrest tells Dan about his plans to buy a shrimp boat, Dan laughs at him and sarcastically tells him that if his dream ever comes true, he will be Forrest's first mate. Meanwhile, Jenny gets addicted to drugs and continues to go from one abusive relationship to another.
Forrest is discharged from the army and is asked to endorse a ping pong paddle, which earns him $25,000. With this money, he buys a shrimping boat, keeping his promise to Bubba. He names the boat Jenny, but has little success with it. Dan keeps his promise to Forrest and he joins him in his shrimping endeavors.
When Hurricane Carmen destroys all the boats except for the "Jenny," Forrest becomes a successful shrimper. Immediately after his success comes, Forrest discovers his mother is dying of cancer, and he returns home to her. Dan invests Forrest’s part of the money into Apple Computers, earning Forrest a fortune.
One day, Jenny visits Forrest and stays with him for a while. When Forrest proposes to her, she declines, but they end up having sex that night. The next day, Jenny leaves Forrest.
Distraught, Forrest starts running around the country without stopping, except to sleep and eat. His persistent running turns him into a celebrity, and he even catches Jenny's attention.
When the scene shifts back to the present on the bench at the bus stop, Forrest tells the woman sitting next to him that he is in Savannah to visit Jenny, who wrote to him. When Forrest goes to see Jenny, she introduces him to her son, Forrest. Jenny tells Forrest that the boy is his and that she is sick with an unknown virus.
The three move to Greenbow and Jenny and Forrest get married. Dan comes to the wedding with his fiancé. Dan is no longer in a wheelchair, but has prosthetic legs.
Forrest lives happily with Jenny and Forrest Jr., but Jenny eventually dies. The last scene in the film shows Forrest sending Forrest Jr. to the bus on his first day of school.
