Sonia Sotomayor was born in the New York City borough of The Bronx.  Her father was Juan Sotomayor (c. 1921–1964), from the area of Santurce, San Juan, Puerto Rico, and her mother was Celina Báez (1927–2021), from the neighborhood of Santa Rosa in Lajas, a farm area on Puerto Rico's southwest coast.

She was raised a Catholic and grew up in Puerto Rican communities in the South Bronx and East Bronx. The family lived in a South Bronx tenement before moving in 1957 to the well-maintained, racially and ethnically mixed, working-class Bronxdale Houses housing project in Soundview, Bronx. 

Sotomayor passed the entrance tests for and then attended Cardinal Spellman High School in the Bronx, where she was on the forensics team and was elected to the student government. She graduated as valedictorian in 1972. 

Sotomayor entered Princeton University in 1973 on a full scholarship, by her own later description gaining admission in part due to her achievements in high school and in part because affirmative actions made up for her standardized test scores not being fully comparable to those of other applicants. She earned a B.A. in 1976 graduating summa cum laude and receiving the university’s highest academic honor. 

Sotomayor entered Yale Law School in the fall of 1976, once more on a scholarship. While she believes she again benefited from an affirmative action to compensate for somewhat lower standardized test scores, a former dean of admissions at Yale has said that given her record at Princeton, it probably had little effect. At Yale she fit in well although she found there were again few Latino students. She was known as a hard worker but she was not considered among the star students in her class. She became an editor of the Yale Law Journal and was also manage editor of the student-run Yale Studies in World Public Order publication. Sotomayor published a law review note on the effect of possible Puerto Rican statehood on the island's mineral and ocean rights.

Following her second year, she gained a job as a summer associate with the prominent New York law firm Paul, Weiss, Rifkind, Wharton & Garrison. By her own later evaluation, her performance there was lacking. She did not receive an offer for a full-time position, an experience that she later described as a "kick in the teeth" and one that would bother her for years. In her third year, she filed a formal complaint against the established Washington, D.C., law firm of Shaw, Pittman, Potts & Trowbridge for suggesting during a recruiting dinner that she was at Yale only via affirmative action. Sotomayor refused to be interviewed by the firm further and filed her complaint with a faculty–student tribunal, which ruled in her favor. Her action triggered a campus-wide debate, and news of the firm's subsequent December 1978 apology made The Washington Post. In 1979, she earned a J.D. from Yale Law School.

From 1979 to 1984, Sonia Sotomayor served as Assistant District Attorney in the New York County District Attorney’s Office. She then litigated international commercial matters in New York City at Pavia & Harcourt, where she acted as an associate and then partner from 1984 to 1992. In 1991, President George H.W. Bush nominated her to the U.S. District Court, Southern District of New York, where she served from 1992 to 1998. She served as a judge on the United States Court of Appeals for the Second Circuit from 1998 to 2009. 

On May 25th, 2009, president Barack Obama appointed Sotomayor to the Supreme Court. On July 28th, the Senate Judiciary Committee voted 13–6 in favor of Sotomayor's nomination and addressed it to the full Senate for a final confirmation vote. Every Democrat voted in her favor, as did one Republican, Lindsey Graham. On August 6th, 2009, Sotomayor was confirmed by the full Senate by a vote of 68–31. All Democrats present, along with the Senate's two Independents plus nine Republicans, voted for her. On August 8th that year she was sworn in the Supreme Court Building. 

See: Supreme Court