Legendary singer Andy Williams, known for his smooth voice and classics such as "Moon River," died after a year-long battle with bladder cancer at his Branson, Missouri, home Tuesday night, his family said.

Williams, 84, began his singing career as a child in a quartet with his brothers, but he rose to stardom as a solo act starting in the 1950s.

"The Andy Williams Show," a weekly television variety program that ran for nine years on NBC starting in 1962, and a dozen TV specials from 1959 through 1987 made Williams a household name in the United States.

He spent the last 20 years of his career performing on his own stage at his Moon River Theatre in Branson.

Jimmy Osmond said his family would be "forever grateful for the interactions we had with him."

"Not only did he discover us as a group, but also allowed us the opportunity to be discovered as individuals and develop our own talents," Osmond said.

"The clarity and warmth and grace of his singing shaped my love of music as I watched my brothers perform with him on his weekly show," Donny Osmond said.

Williams gave him several voice lessons when he was just 7, Osmond said.

"When I finally joined my brothers and toured with Andy as his opening act and back-up singers, I was always impressed with the way he handled an audience," he said. "He loved the audience. That was one of the most important lessons he taught me."

His sister, Marie Osmond, who made her TV debut on his show at age 3, said Williams was "the first person to affect my career."

"The group 'The Osmonds' would not exist without the foresight and generosity of our mentor Andy Williams," Marie Osmond said.

"No one sang more beautifully than Andy Williams," she said. "Hearing his version of 'Moon River' never failed to move me deeply. I can't imagine the holiday season without Andy Williams; we did so many specials together."

"Moon River" became his theme song after he performed it at the 1962 Academy Awards, where it won an Oscar for best song in a movie. Audrey Hepburn sang the Johnny Mercer and Henry Mancini composition in the film "Breakfast at Tiffany's."

Williams' recording career reached superstar status in 1963 when his album "Days of Wine and Roses" spent 16 weeks at the top of the U.S. music charts.

His variety TV show, which promoted the careers of many other artists including the Osmonds, won high ratings and three Emmys.

Singer Ray Stevens, who was managed for years by Andy's brother Don, called him "one classy guy."

"He was a marvelously talented and generous performer who in 1970 entrusted his nationally acclaimed TV show and audience to a green kid from Georgia," Stevens said. "That kid was me, and he changed my life."

Williams hosted the first live Grammy Awards telecast at the Hollywood Palladium in 1971. He went on to host for seven years straight.

"The entertainment industry has lost a giant piece of its living history today, but Williams' legacy will forever be enshrined in the annals of music and television," said Neil Portnow, the president of the National Academy of Recording Arts and Sciences. "Our deepest condolences go out to his family, friends, and all who will miss this American treasure."

The singer hosted five Christmas television specials, between 1973 and 1985, along with seven other television specials, the first in 1959 and the last in 1987.