In 1932, Christy Brown is born into a Dublin family of 15. Doctors discover he has severe cerebral palsy. Christy is unable to walk or talk. He is loved and supported by his family, especially his mother. One day, Christy's mother trips down the stairs while in labour and Christy was the only person home to see it. He alerted some neighbours to help. Christy's father had never believed Christy would amount to anything, but becomes proud after witnessing him use his left foot, the only body part he can fully control, to write the word "mother" on the floor with a piece of chalk.
Consequently, Christy seeks a hobby in painting. The neighbourhood youngsters include him in their activities, like street football, but when he paints a picture and gives it to a girl he likes, she returns it. Later, his father loses his job and the family faces exceptionally difficult hardships, so Christy devises a plan to help his brothers steal coal to their mother's dismay. Christy's mother, who had been gradually gathering some savings in a tin in the fireplace, finally saves enough to buy him a wheelchair.
Christy is then introduced to Eileen Cole, who takes him to her school for cerebral palsy patients and persuades a friend of hers to hold an exhibition of his work. Christy falls in love with Cole, but when he learns during the dinner that she is engaged to be married, he considers suicide. His mother helps him build a private studio for himself, but soon afterward his father dies of a stroke, and during the wake Christy instigates a brawl. At this point, Christy starts writing his autobiography, My Left Foot. Cole returns and they resume their friendship. Later, Christy attends a charity event where he meets his handler, a nurse named Mary Carr. She begins reading his autobiography. He asks Mary to go out with him and they then happily leave the fete together.
