Jane Bolin, who was the first black woman to graduate from Yale Law School and became the nation’s first black female judge, has died at age 98.

Ms. Bolin was sworn in by Mayor Fiorello H. La Guardia in a surprise ceremony in 1939, becoming the first black female judge in the United States, according to the city’s law department.

Assigned to the Domestic Relations Court, later renamed Family Court, Ms. Bolin fought racial discrimination from the bench. She worked to end segregation in child placement facilities and the assignment of probation officers based on race. She also helped to create a racially integrated treatment center for delinquent boys.

Ms. Bolin reflected on her status as a barrier-breaker in a 1993 interview with The New York Times.

“Everyone else makes a fuss about it, but I didn’t think about it, and I still don’t,” she said. ‘‘I wasn’t concerned about first, second or last. My work was my primary concern.”

Her 10-year appointment was renewed by the city’s mayors three times until she reached the mandatory retirement age of 70.

In a speech in 1958, Ms. Bolin discussed women’s struggle for equal rights.

‘‘Those gains we have made were never graciously and generously granted,” she said. ‘‘We have had to fight every inch of the way, in the face of sometimes insufferable humiliations.”

Ms. Bolin, born on April 11, 1908, in Poughkeepsie, N.Y., was the daughter of a successful lawyer. Initially discouraged by a Wellesley College adviser from pursuing a law degree because of her race and gender, Ms. Bolin persevered, graduating from Yale Law School in 1931.

She practiced law with her father in Poughkeepsie and later with her husband, Ralph Mizelle, in New York. Years before it was common, she decided to keep her maiden name.

Explaining her decision to leave her hometown, Ms. Bolin said in 1944 that it was ‘‘fascist to the extent of deluding itself that there is superiority among human beings by reason solely of color or race or religion.”

Ms. Bolin initially met resistance when she applied to work for New York’s law department, but in 1937 she became the first black person to serve as an assistant corporation counsel in the city. She continued at the job until two years later, when the mayor called her in for what she was certain was a reprimand. Instead, she was sworn in to the bench.

Ms. Bolin is survived by her son, Yorke B. Mizelle.

Her first husband died in 1943. Her second husband, clergyman Walter Offutt Jr., died in 1974 after nearly 25 years of marriage.