Magali García Ramis was born in 1946 in Santurce, Puerto Rico. She lived all her childhood in this borough of San Juan, with her mother, father and brothers, near her mother's family, with close relations with uncles, cousins and her maternal grandmother. Her father worked as a civil servant in Fort Buchanan; her mother worked for a while in her sister's laboratory and later stayed home with her children. Her eldest aunt, María Luisa Ramis, was the first woman in Puerto Rico to open a laboratory and all the aunts worked there. García Ramis spent many hours of her childhood in her grandmother's house and in the laboratory.

When García Ramis was a teenager, her family moved to the upscale Miramar section and she and her elder brother had to change schools. She enrolled at the Academia del Perpetuo Socorro (Academy of Our Lady of Perpetual Help), where she graduated from high school. That school emphasized American culture and history, and García Ramis and many classmates, comparing the U.S. and Puerto Rico interpreted all things American as being better than those of the island. García Ramis always struggled with this idea and in college she learned more about Puerto Rican culture. These themes can be found in her literary work.

In 1964 she enrolled at the University of Puerto Rico where she majored in History. After graduating, she worked for the newspaper El Mundo. In 1968 she received a scholarship and moved to New York City to study journalism at Columbia University. It is in New York that she writes her first story, "Todos los domingos" ("Every Sunday"). With this story she won first prize in the literary contest of the Ateneo Puertorriqueño (Puerto Rican Athenaeum). She returned to Puerto Rico in 1971 and started to work for the newspaper El Imparcial. She worked for the newspaper until 1972. She also worked for a literary magazine called Avance until 1973. During this period she continued to write short stories.

García Ramis sent a book composed of 4 short stories to a contest sponsored by the Casa de las Américas in Cuba. She received an honorary mention for one of the stories "La viuda de Chencho el Loco" ("The Widow of Chencho, the Mad Man") which was published in 1974. That same year she moved to Mexico. She returned to Puerto Rico in 1977 and published another book of short stories called La familia de todos nosotros. She also started to work for the School of Communications at the University of Puerto Rico. She routinely collaborated in several Puerto Rican newspapers.

She finished her famous semi-autographical novel Felices días, tío Sergio (Happy Days, Uncle Sergio) in 1985; it was published in 1986. In 1988, she received a Guggenheim Fellowship for her second novel, Las horas del Sur (The Hours of the South).

In 1993, García Ramis published La ciudad que me habita (The City that Inhabits Me), a collection of journalistic essays that she wrote while she worked for El Mundo, El Imparcial, Avance, Claridad and La Hora.

García Ramis's stories are depictions of Puerto Rican culture, family and politics. She writes about interactions within a family, Puerto Rican identity and women's identity. In her best known novel Happy Days, Uncle Sergio, she explores the relationship between a young Puerto Rican tomboy and her uncle, who is rumored to be a homosexual.