According to the Las Vegas Sun, Phyllis died at her home, which she called "the Beverly Hills of Las Vegas," in the Rancho Circle estates near downtown Las Vegas.
The 26,000-square-foot mansion includes a 45-foot replica of the Eiffel Tower.
Phyllis and her sisters -- Dorothy and Christine -- were best known for their pop hits "Sincerely," "Sugartime" and "Goodnight, Sweetheart, Goodnight." They earned multiple gold records throughout their career.
They were also known for their tight harmonies and matching outfits.
Well revered, the trio performed for a number of high-profile politicians including five United States presidents and even Queen Elizabeth II.
They were inducted into the National Broadcasting Hall of Fame in 1994 and the Vocal Group Hall of Fame in 2001.
The McGuire Sisters began their musical journey by singing at their mother’s Ohio church before transitioning to performing at weddings.
In 1952, the trio appeared on "The Kate Smith Show," launching them to stardom.
Phyllis was portrayed by Mary-Louise Parker in HBO's "Sugartime," which chronicled the singer's romance with mob boss Sam Giancana.
The musician was married to Neal Van Ells from 1952-1956.
Phyllis was born in Middletown, Ohio, in 1931. Dorothy and Christine died in 2012 and 2018, respectively.
The Associated Press contributed to this report.