Felix Frankfurter was born in Vienna, Austria in 1882. His family immigrated to the United States in 1894, when Frankfurter was 12. Although Frankfurter knew no English when his family settled in New York, his intellectual brilliance and ambition took him in 1897 to the City College of New York, where he completed a program combining part of high school and all of college in 1902. He graduated with high honors. After spending a year working for New York City's Housing Department, Frankfurter attended Harvard Law School. Frankfurter graduated first in the class of 1906. After a short time in private practice, Frankfurter worked for three years as an Assistant United States Attorney in New York under Henry Stimson, later a Secretary of War under three Presidents, and a Secretary of State under another President. When Stimson was appointed Secretary of War by President Taft, Frankfurter moved to Washington, D.C. and joined the War Department as a legal counsel. In 1914, Frankfurter joined the faculty of the Harvard Law School. He would remain at Harvard until his appointment to the Supreme Court.

Frankfurter was a political progressive, and intensely interested in politics. During his time at Harvard, Frankfurter did not shy away from public affairs. From 1916-18, President Woodrow Wilson used Frankfurter to investigate a growing number of labor disputes and controversies. One of the most controversial cases of the 1920s was the criminal conviction of two Italian immigrants, Sacco and Vanzetti, on charges of murder. To its critics, including Frankfurter, the public's fear that Sacco and Vanzetti were anarchists resulted in a trial that failed to meet the standards guaranteed by the Constitution to any criminally accused person. Frankfurter was often vilified as a "red" during this time, and some Harvard alumni demanded his firing from the law school. Frankfurter also occasionally made arguments before the Supreme Court in cases in which progressive ideals were at issue. Although Frankfurter wrote a number of scholarly works, he was better known as a contributor of essays and articles to the New Republic, a magazine founded by like-minded progressives. Although Frankfurter remained at Harvard, he exerted some influence in Washington. Justices Oliver Wendell Holmes and Louis D. Brandeis left to Frankfurter the appointment of their "secretaries," later called law clerks. These secretaries were invariably Frankfurter's brightest students, many of whom later worked in the federal government during the New Deal administration of Franklin D. Roosevelt. Frankfurter himself flattered and courted FDR, and visited the White House often. His influence on FDR, who listened to the opinions of many different advisers, both in and out of government, is difficult to discern, but when FDR was given the opportunity to remake the Supreme Court between 1937-41, Frankfurter became the third of eight (including the promotion of Harlan Fiske Stone to Chief Justice from Associate Justice) appointees to the Court.

Frankfurter was appointed to the seat held by Justice Benjamin N. Cardozo, a seat that had also been occupied by Justice Holmes and Justice Joseph Story. Frankfurter was only the third Jewish Justice appointed to the Supreme Court (following Cardozo and Brandeis), and was the first nominee of the Court to testify before the Senate Judiciary Committee. The appointment of Frankfurter and other political liberals and progressives, many believed, would transform the Court. It didn't, and the reason why it didn't aids us in understanding the perceptions about and of the Court today. Frankfurter was a political liberal who disparaged legal formalism and who believed in judicial restraint. In Frankfurter's view, some of his colleagues, most notably Justices Hugo Black and William O. Douglas, too regularly adapted their principles to reach a result politically palatable to each. The seeds of the divisions between Black and Douglas, on the one hand, and Frankfurter on the other, may have been sown in the first flag salute case, Minersville Sch. Dist. v. Gobitis, decided in 1940. The Court, in an opinion by Frankfurter, concluded that a public school was permitted to expel a student who refused, for religious reasons, to salute the American flag. Only Justice Stone dissented. Within a year, it appeared to Frankfurter that Black and Douglas were planning on reversing Gobitis not for legal, but for political reasons. To Frankfurter, this was anathema. When the Court did overrule Gobitis in 1943 in West Virginia Board of Education v. Barnette, the relationship between these progressive Justices broke down. The relationship among the members of the Court was further harmed when Justices Black and Robert H. Jackson found themselves in a bitter dispute over Black's decision not to recuse himself in a case involving his former law partner, particularly when the case was decided 5-4 in favor of the party represented by the former partner, and when, upon Owen J. Roberts's resignation in 1945, the remaining members of the Court fought over the language of a letter congratulating Roberts about his service on the Court. Although possibly apocryphal, there are stories that Douglas would ostentatiously leave the conference table when Frankfurter began stating his opinion of a pending case, and return only after Frankfurter had finished speaking. Another story is that Douglas, after hearing Frankfurter speak, said, "I was going to vote as Felix says he is, but he convinced that I should vote otherwise." Although Black and Frankfurter would eventually reconcile, Douglas and Frankfurter never did.

During the 1950s and early 1960s, Frankfurter's vision of judicial restraint appeared increasingly out of step with a majority of the Court. In 1962, Frankfurter suffered a stroke. He retired from the Court that year, after 23 years on the Court. Frankfurter died in 1965. He was survived by his wife, Marion A. Denman, the daughter of a Presbyterian minister. They were married by Cardozo in December 1919. They did not have any children.