Alice Tan Ridley, who rose to fame after decades singing for tips in the New York City subway with an unexpected run in the television show “America’s Got Talent,” died on March 25 in New York City. Ms. Ridley, who was the mother of the Oscar-nominated actress Gabourey Sidibe, was 72.

Her family announced the death in an obituary published online. It did not cite a cause.

Ms. Ridley’s public life as a singer began underground in the mid-1980s, and she spent decades belting out songs in New York City subway stations. At first, the subway busking was meant to supplement income from her day job in education. Eventually, she quit to sing full time.

In her early days of busking, the performances were collaborations with her brother Roger Ridley and their cousin Jimmy McMillan, the political activist who would become famous for founding the Rent Is Too Damn High Party in New York.

“We are not homeless,” she told “Good Morning America” in 2010, referring to buskers. “We are not beggars. And we’re not under drug influence, you know? There are traditional jobs, and there are nontraditional jobs.”

She compared busking in New York to “being in a cathedral.”

“It’s wonderful,” she said. “There’s just music all over this city, and especially down underground.”

For Ms. Ridley, singing underground fulfilled a calling. In 2005, she appeared in the film “Heights,” directed by Chris Terrio, as a subway singer.

“People always say, ‘Why don’t you sing in clubs?’ ” Ms. Ridley told The New York Post in 2010. “I tell them, ‘This is my club.’”

Her big break came that year when she auditioned for “America’s Got Talent.” Typically, most contestants on competition shows are younger, but Ms. Ridley was in her late 50s. In her audition, she impressed the judges with her rendition of the Etta James classic “At Last.” She would be eliminated in the semifinals, but not before delivering other highly praised performances, including renditions of “Proud Mary” and “Midnight Train to Georgia.”

The talent show stint kicked off her career above ground, and she began touring worldwide. Finding the travel grueling, Ms. Ridley returned to busking in 2014.

“When I was no longer down under there,” Ms. Ridley told The New York Times in 2016, “I missed it.”

That same year, she released her debut album, “Never Lost My Way.”

Alice Tan Ridley, the daughter of Melton Lee and Lessie B. Ridley, was born Alice Ann Ridley on Dec. 21, 1952. She grew up in a large musical family in Lumpkin, Ga.

“My mother was my greatest influence,” she told The Morning Call in 2013, referring to her mother, Lessie. “She wrote songs and plays and had us all singing.”

Her father, Melton Lee, was a guitar player. Roger, her older sibling, was also a street musician who played around the country and became prominent after appearing in performances for “Playing for Change,” a project that unites musicians across the world.

She graduated from Stewart County High School in Lumpkin, Ga., around 1969, before moving to New York, where she had visited during summer breaks in high school. Ms. Ridley married Ibnou Sidibe, who was then a cabdriver, around 1980.

They had two children, Ahmed Sidibe and Gabourey Sidibe, before their marriage ended in divorce in the early 1990s. Ms. Ridley is also survived by two brothers, James D. Ridley and Tommy Lee Cherry; two sisters, Julia Van Mater-Miller and Mildred Ridley Dent; and two grandchildren.

Singing was a third career for Ms. Ridley. In the early 1970s, she worked as a nursery teacher after moving to New York. In 1976, Ms. Ridley took a job as a teacher’s aide for special needs children at a public elementary school in New York.

The year before Ms. Ridley appeared on “America’s Got Talent,” her daughter, Ms. Sidibe, hit it big: She starred in the movie “Precious,” a role for which Ms. Sidibe was nominated for an Oscar. The role came about, in part, because of Ms. Ridley. From her telling, she was approached to be in the movie.

“They asked me to play the part of the mother,” Ms. Ridley told The Post in the 2010 interview. “But being a mom and teacher, I just couldn’t play that part. It was just too hard.”

The movie is an adaptation of the 1996 novel “Push” by Sapphire.

“I read the book, and I gave it to Gabby,” Ms. Ridley said. “Her friends encouraged her to try out for ‘Precious,’ and she got it.” At the time, Ms. Sidibe was a psychology student secretly working as a phone-sex operator.

In the “Good Morning America” interview, Ms. Ridley recalled how she told her children that they “can be whatever you want to be.”

“You can do whatever you want to do,” Ms. Ridley said. “You just have to get up and do it.”

In Ms. Ridley’s case, she wanted to be a singer — no matter where.

“Travelers would be worried about their mortgages, getting fired and their jobs,” Ms. Ridley told The Toronto Star in 2012. “They would pass by me and see me singing. They would stand by me for two or three hours, hang with me in the heat all sweating or as cold as the dickens because they were entertained.”

She added, “I brought a little joy to people who were traveling.”