Patty Andrews, the youngest and last surviving member of the Andrews Sisters, a vocal trio whose music was a defining sound of the homefront during World War II, died Jan. 30 at her home in Northridge, Calif. She was 94.

Her attorney, Richard Rosenthal, confirmed the death but did not disclose the specific cause.

Ms. Andrews was lead singer in the sister act, which included the eldest, LaVerne, and second-born Maxene. Their recordings — including “Boogie Woogie Bugle Boy,” “Don’t Sit Under the Apple Tree (With Anyone Else But Me),” “Rum and Coca Cola” — helped propel them to the top of the pop charts in the 1940s.

Their songs varied from sentimental ballads to rollicking, jitterbuggable jazz, and they also developed a slapstick stage persona that emanated from their early days in vaudeville. A handful of film roles in the early 1940s captured their multifaceted appeal.

Promoted as the “Sweethearts of the Armed Forces Radio Service,” they also toured extensively to raise money for war bonds and appeared in combat zones to raise morale.

The Andrews Sister — from left, Maxene, Patty and LaVerne — in 1945. Patty Andrews, the last surviving member, died Jan. 30. (CBS/Metronome/GETTY IMAGES)

The Andrews Sisters played with the most popular big bands of the 1940s, including those of Benny Goodman, Glenn Miller and Jimmy Dorsey. They were credited with selling tens of millions of records, and they influenced countless other harmony groups.

Many of their songs were covered by entertainers as varied as Bette Midler, Christina Aguilera and the Manhattan Transfer, and their clothing style was widely imitated as well by groups seeking to evoke the spirit of 1940s pop music. The Andrews Sisters were among the initial inductees into the Vocal Group Hall of Fame in 1998.

Patricia Marie Andrews was born Feb. 16, 1918, in Mound, Minn., to a Greek immigrant father who had anglicized his surname and a Norwegian American mother. The sisters began singing as children and performed professionally from a young age at Minneapolis theaters.

The Andrews Sisters modeled themselves on the Boswell Sisters, a major recording and radio singing group, but they also perfected a harmonizing style deeply influenced by the trumpet section of a big band, Patty Andrews once said.

They toured in vaudeville and eventually broke through on radio and had their first hit record in 1937 with a raucously jazzy version of a Yiddish tune, “Bei Mir Bist Du Schön.”

“We decided to sing a Yiddish song because we were Greek,” Patty Andrews told the London Independent in 1990. “We wanted to break into the Jewish resort circuit in the Catskill Mountains. We figured Greek girls singing Yiddish would knock ’em dead.”

A series of hit records, including “Beat Me Daddy, Eight to the Bar,” led them to a Hollywood contract and a flurry of movie roles in comedies such as “In the Navy,” “Private Buckaroo” and “Follow the Boys.” The sisters, who had accompanied Bing Crosby on his million-dollar seller “Don’t Fence Me In,” appeared as themselves opposite Crosby and Bob Hope in the comedy “Road to Rio” (1947).

The group broke up in 1951 when Patty Andrews left to join another group, and her siblings were reportedly furious when they first learned the news through a newspaper article. The relationships among the sisters dissolved into a morass of lawsuits and quarreling over compensation.

Ms. Andrews became a featured soloist at Capitol Records before reuniting with her sisters in the mid-1950s. Despite family tensions, they continued to record and perform together until LaVerne died of cancer in 1967.

Ms. Andrews’s first marriage, to agent Marty Melcher, ended in divorce, and he subsequently married singer Doris Day. In 1951, Ms. Andrews married Andrews Sisters pianist Walter Weschler. He died in 2010. She had no immediate survivors.

Midler’s early 1970s cover version of “Boogie Woogie Bugle Boy” led to renewed interest in the Andrews Sisters. The revival culminated in the 1974 Broadway musical “Over Here!” that featured Patty and Maxene.

Patty Andrews continued a solo performing career in cabarets and on TV variety programs before retiring in the 1990s after heart attacks. She attempted newer songs but said the wave of nostalgia was ultimately too hard to fight and gave the audience what it wanted: much of the old Andrews Sisters songbook.

Maxene died in 1995. The sisters seldom socialized with one another, despite the proximity of their homes. Ms. Andrews rarely granted interviews and tried to avoid talking of her sisters and their long feud.

“I’m not going to do anything or say anything to destroy that image that the people love,” she once told the Los Angeles Times. “I hear that from the people that they love the Andrews Sisters and it’s a joy to them. Who am I to take that away?”